LIU meeting 1

LLRF FOR THE SPS 800 MHZ CAVITIES

G Hagmann P Baudrenghien

12122013

LIU meeting 2

Block diagram12122013

LIU meeting 3

800 MHz TX-cavity chain

Cavity

12122013

Centre freq 800888 MHz

Phase advance per cell p2

Group velocity vgc +0035

Cell length 935 mm

Total length L (37 cells) 3460 m

Series impedance R2 0647 MWm

3145 MHz

2

20 2 2

2

sin sin sin2 2 22 8

2 2

1

RF b

g

g

Z R L RV L I j I

vLv v

LIU meeting 4

800 MHz TX-cavity chain (contrsquod)

TX (IOT) 1 dB 3 MHz-4 dB 5 MHz

12122013

Measurement reproduced from Ericrsquos presentation

Conclusion We aim at minimum plusmn6 MHz Closed-Loop bandwidth

Vector sum

12122013 LIU meeting 5

New 800 MHz System (VME)

LL Cavity 1 LL Cavity 2

12122013 LIU meeting 6

LL Cavity 1 LL Cavity 2LL Common

New 800 MHz System (VME)

RFFGCMM SwitchampLimitCavity Loops 200MHZ

Quadrupler

Clock Distributor

Linux FrontEnd CTRV

VME

bus

(A24

D16

)R

F Lo

wLe

vel

Bac

kpla

ne

12122013 LIU meeting 7

VME Cards

Switch amp Limit Clock Distributor

RF design amp FPGA (Controls Acquisitionshellip) on the same board

12122013 LIU meeting 8

JLollierou JNoirejan GHagmannGHagmann

VME Cards

200MHZ Quadrupler

12122013 LIU meeting 9

RF Function generator

MNaon TLevens GHagmann

GHagmann

12122013 LIU meeting 10

3rd HiLumi LHC-LARP

SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits

RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz

4x

LO Distribution

2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)

SRAM 2x8 Mbyte for diagnostics

VME P1 backplane

for slow controlsread

out

Dedicated backplane (P2)

bull Power Supplybull Clocksbull Interlocksbull hellip

Xilinx Virtex-5 SXT

G Hagmann BE-RF-FBdesigner

Cavity Loops v1

Module Name Status 122012 Status 122013 Software

Linux Front-end (CPU)

Installed Installed NR

CTRV (timing) Installed Installed OK

CMM(Crate Management)

Installed Installed OK

WBS(Wide Band Switch)

LHC Spares available LHC Spares available -

RFFG(Function generator)

under design Installed OK

SwitchampLimit Proto V2 under test V3 pre-series in prod From L4

Clock Distributor Proto V2 under test Proto V3 under test From L4

200MHz Quadrupler Proto V1 in prod V2 in prod NR

Cavity Loops(RF Feedback)

Under design V1 available From L4

Veto Sum Under specification Under specification -

Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR

Status

12122013 LIU meeting 11

Cavity Loop IQ demodulationTWC 800 MHz Frequencies

LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz

Fs

12122013 LIU meeting 12

Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits

The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS

Fine delay(1 Turn)

RF Function Receiver(VoltagePhase offset Setpoint)

Longitudinal Damper(From Beam Control Optical Gbit link)

Ref Phase from 200MHz Cavity Σ

Comb filter(Beam synchronous

clock)

Cavity filter(Absolute Cavity

response)

Feed forward(Beam synch clock)

Polar Loop

In-situ Observation

ampBBNANoise

(Blow-up)

RF Modulator(Single side band Transmitter)

12122013 LIU meeting 13

Ref Phase 200MHz Cavity Σ + setPoint

Comb filter=gt Gain plusmn n∙frev plusmn m∙fs

Cavity filter=gt Sign Inversion

cavity zeros

FiFo1T-delay

NCOupampdown Modulation

RF Modulator

TWC 200 MHz Phase ΣφsetPoint

4x TWC200 Σ

TWC800

Bunch lengthening Bunch shortening

12122013 LIU meeting 14

TWC200 Σ

Filters (implementation)

Beat frequency computation (from pre-defined function)

Downup modulation

12122013 LIU meeting 15

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

LIU meeting 2

Block diagram12122013

LIU meeting 3

800 MHz TX-cavity chain

Cavity

12122013

Centre freq 800888 MHz

Phase advance per cell p2

Group velocity vgc +0035

Cell length 935 mm

Total length L (37 cells) 3460 m

Series impedance R2 0647 MWm

3145 MHz

2

20 2 2

2

sin sin sin2 2 22 8

2 2

1

RF b

g

g

Z R L RV L I j I

vLv v

LIU meeting 4

800 MHz TX-cavity chain (contrsquod)

TX (IOT) 1 dB 3 MHz-4 dB 5 MHz

12122013

Measurement reproduced from Ericrsquos presentation

Conclusion We aim at minimum plusmn6 MHz Closed-Loop bandwidth

Vector sum

12122013 LIU meeting 5

New 800 MHz System (VME)

LL Cavity 1 LL Cavity 2

12122013 LIU meeting 6

LL Cavity 1 LL Cavity 2LL Common

New 800 MHz System (VME)

RFFGCMM SwitchampLimitCavity Loops 200MHZ

Quadrupler

Clock Distributor

Linux FrontEnd CTRV

VME

bus

(A24

D16

)R

F Lo

wLe

vel

Bac

kpla

ne

12122013 LIU meeting 7

VME Cards

Switch amp Limit Clock Distributor

RF design amp FPGA (Controls Acquisitionshellip) on the same board

12122013 LIU meeting 8

JLollierou JNoirejan GHagmannGHagmann

VME Cards

200MHZ Quadrupler

12122013 LIU meeting 9

RF Function generator

MNaon TLevens GHagmann

GHagmann

12122013 LIU meeting 10

3rd HiLumi LHC-LARP

SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits

RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz

4x

LO Distribution

2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)

SRAM 2x8 Mbyte for diagnostics

VME P1 backplane

for slow controlsread

out

Dedicated backplane (P2)

bull Power Supplybull Clocksbull Interlocksbull hellip

Xilinx Virtex-5 SXT

G Hagmann BE-RF-FBdesigner

Cavity Loops v1

Module Name Status 122012 Status 122013 Software

Linux Front-end (CPU)

Installed Installed NR

CTRV (timing) Installed Installed OK

CMM(Crate Management)

Installed Installed OK

WBS(Wide Band Switch)

LHC Spares available LHC Spares available -

RFFG(Function generator)

under design Installed OK

SwitchampLimit Proto V2 under test V3 pre-series in prod From L4

Clock Distributor Proto V2 under test Proto V3 under test From L4

200MHz Quadrupler Proto V1 in prod V2 in prod NR

Cavity Loops(RF Feedback)

Under design V1 available From L4

Veto Sum Under specification Under specification -

Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR

Status

12122013 LIU meeting 11

Cavity Loop IQ demodulationTWC 800 MHz Frequencies

LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz

Fs

12122013 LIU meeting 12

Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits

The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS

Fine delay(1 Turn)

RF Function Receiver(VoltagePhase offset Setpoint)

Longitudinal Damper(From Beam Control Optical Gbit link)

Ref Phase from 200MHz Cavity Σ

Comb filter(Beam synchronous

clock)

Cavity filter(Absolute Cavity

response)

Feed forward(Beam synch clock)

Polar Loop

In-situ Observation

ampBBNANoise

(Blow-up)

RF Modulator(Single side band Transmitter)

12122013 LIU meeting 13

Ref Phase 200MHz Cavity Σ + setPoint

Comb filter=gt Gain plusmn n∙frev plusmn m∙fs

Cavity filter=gt Sign Inversion

cavity zeros

FiFo1T-delay

NCOupampdown Modulation

RF Modulator

TWC 200 MHz Phase ΣφsetPoint

4x TWC200 Σ

TWC800

Bunch lengthening Bunch shortening

12122013 LIU meeting 14

TWC200 Σ

Filters (implementation)

Beat frequency computation (from pre-defined function)

Downup modulation

12122013 LIU meeting 15

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

LIU meeting 3

800 MHz TX-cavity chain

Cavity

12122013

Centre freq 800888 MHz

Phase advance per cell p2

Group velocity vgc +0035

Cell length 935 mm

Total length L (37 cells) 3460 m

Series impedance R2 0647 MWm

3145 MHz

2

20 2 2

2

sin sin sin2 2 22 8

2 2

1

RF b

g

g

Z R L RV L I j I

vLv v

LIU meeting 4

800 MHz TX-cavity chain (contrsquod)

TX (IOT) 1 dB 3 MHz-4 dB 5 MHz

12122013

Measurement reproduced from Ericrsquos presentation

Conclusion We aim at minimum plusmn6 MHz Closed-Loop bandwidth

Vector sum

12122013 LIU meeting 5

New 800 MHz System (VME)

LL Cavity 1 LL Cavity 2

12122013 LIU meeting 6

LL Cavity 1 LL Cavity 2LL Common

New 800 MHz System (VME)

RFFGCMM SwitchampLimitCavity Loops 200MHZ

Quadrupler

Clock Distributor

Linux FrontEnd CTRV

VME

bus

(A24

D16

)R

F Lo

wLe

vel

Bac

kpla

ne

12122013 LIU meeting 7

VME Cards

Switch amp Limit Clock Distributor

RF design amp FPGA (Controls Acquisitionshellip) on the same board

12122013 LIU meeting 8

JLollierou JNoirejan GHagmannGHagmann

VME Cards

200MHZ Quadrupler

12122013 LIU meeting 9

RF Function generator

MNaon TLevens GHagmann

GHagmann

12122013 LIU meeting 10

3rd HiLumi LHC-LARP

SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits

RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz

4x

LO Distribution

2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)

SRAM 2x8 Mbyte for diagnostics

VME P1 backplane

for slow controlsread

out

Dedicated backplane (P2)

bull Power Supplybull Clocksbull Interlocksbull hellip

Xilinx Virtex-5 SXT

G Hagmann BE-RF-FBdesigner

Cavity Loops v1

Module Name Status 122012 Status 122013 Software

Linux Front-end (CPU)

Installed Installed NR

CTRV (timing) Installed Installed OK

CMM(Crate Management)

Installed Installed OK

WBS(Wide Band Switch)

LHC Spares available LHC Spares available -

RFFG(Function generator)

under design Installed OK

SwitchampLimit Proto V2 under test V3 pre-series in prod From L4

Clock Distributor Proto V2 under test Proto V3 under test From L4

200MHz Quadrupler Proto V1 in prod V2 in prod NR

Cavity Loops(RF Feedback)

Under design V1 available From L4

Veto Sum Under specification Under specification -

Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR

Status

12122013 LIU meeting 11

Cavity Loop IQ demodulationTWC 800 MHz Frequencies

LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz

Fs

12122013 LIU meeting 12

Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits

The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS

Fine delay(1 Turn)

RF Function Receiver(VoltagePhase offset Setpoint)

Longitudinal Damper(From Beam Control Optical Gbit link)

Ref Phase from 200MHz Cavity Σ

Comb filter(Beam synchronous

clock)

Cavity filter(Absolute Cavity

response)

Feed forward(Beam synch clock)

Polar Loop

In-situ Observation

ampBBNANoise

(Blow-up)

RF Modulator(Single side band Transmitter)

12122013 LIU meeting 13

Ref Phase 200MHz Cavity Σ + setPoint

Comb filter=gt Gain plusmn n∙frev plusmn m∙fs

Cavity filter=gt Sign Inversion

cavity zeros

FiFo1T-delay

NCOupampdown Modulation

RF Modulator

TWC 200 MHz Phase ΣφsetPoint

4x TWC200 Σ

TWC800

Bunch lengthening Bunch shortening

12122013 LIU meeting 14

TWC200 Σ

Filters (implementation)

Beat frequency computation (from pre-defined function)

Downup modulation

12122013 LIU meeting 15

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

LIU meeting 4

800 MHz TX-cavity chain (contrsquod)

TX (IOT) 1 dB 3 MHz-4 dB 5 MHz

12122013

Measurement reproduced from Ericrsquos presentation

Conclusion We aim at minimum plusmn6 MHz Closed-Loop bandwidth

Vector sum

12122013 LIU meeting 5

New 800 MHz System (VME)

LL Cavity 1 LL Cavity 2

12122013 LIU meeting 6

LL Cavity 1 LL Cavity 2LL Common

New 800 MHz System (VME)

RFFGCMM SwitchampLimitCavity Loops 200MHZ

Quadrupler

Clock Distributor

Linux FrontEnd CTRV

VME

bus

(A24

D16

)R

F Lo

wLe

vel

Bac

kpla

ne

12122013 LIU meeting 7

VME Cards

Switch amp Limit Clock Distributor

RF design amp FPGA (Controls Acquisitionshellip) on the same board

12122013 LIU meeting 8

JLollierou JNoirejan GHagmannGHagmann

VME Cards

200MHZ Quadrupler

12122013 LIU meeting 9

RF Function generator

MNaon TLevens GHagmann

GHagmann

12122013 LIU meeting 10

3rd HiLumi LHC-LARP

SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits

RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz

4x

LO Distribution

2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)

SRAM 2x8 Mbyte for diagnostics

VME P1 backplane

for slow controlsread

out

Dedicated backplane (P2)

bull Power Supplybull Clocksbull Interlocksbull hellip

Xilinx Virtex-5 SXT

G Hagmann BE-RF-FBdesigner

Cavity Loops v1

Module Name Status 122012 Status 122013 Software

Linux Front-end (CPU)

Installed Installed NR

CTRV (timing) Installed Installed OK

CMM(Crate Management)

Installed Installed OK

WBS(Wide Band Switch)

LHC Spares available LHC Spares available -

RFFG(Function generator)

under design Installed OK

SwitchampLimit Proto V2 under test V3 pre-series in prod From L4

Clock Distributor Proto V2 under test Proto V3 under test From L4

200MHz Quadrupler Proto V1 in prod V2 in prod NR

Cavity Loops(RF Feedback)

Under design V1 available From L4

Veto Sum Under specification Under specification -

Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR

Status

12122013 LIU meeting 11

Cavity Loop IQ demodulationTWC 800 MHz Frequencies

LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz

Fs

12122013 LIU meeting 12

Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits

The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS

Fine delay(1 Turn)

RF Function Receiver(VoltagePhase offset Setpoint)

Longitudinal Damper(From Beam Control Optical Gbit link)

Ref Phase from 200MHz Cavity Σ

Comb filter(Beam synchronous

clock)

Cavity filter(Absolute Cavity

response)

Feed forward(Beam synch clock)

Polar Loop

In-situ Observation

ampBBNANoise

(Blow-up)

RF Modulator(Single side band Transmitter)

12122013 LIU meeting 13

Ref Phase 200MHz Cavity Σ + setPoint

Comb filter=gt Gain plusmn n∙frev plusmn m∙fs

Cavity filter=gt Sign Inversion

cavity zeros

FiFo1T-delay

NCOupampdown Modulation

RF Modulator

TWC 200 MHz Phase ΣφsetPoint

4x TWC200 Σ

TWC800

Bunch lengthening Bunch shortening

12122013 LIU meeting 14

TWC200 Σ

Filters (implementation)

Beat frequency computation (from pre-defined function)

Downup modulation

12122013 LIU meeting 15

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

Vector sum

12122013 LIU meeting 5

New 800 MHz System (VME)

LL Cavity 1 LL Cavity 2

12122013 LIU meeting 6

LL Cavity 1 LL Cavity 2LL Common

New 800 MHz System (VME)

RFFGCMM SwitchampLimitCavity Loops 200MHZ

Quadrupler

Clock Distributor

Linux FrontEnd CTRV

VME

bus

(A24

D16

)R

F Lo

wLe

vel

Bac

kpla

ne

12122013 LIU meeting 7

VME Cards

Switch amp Limit Clock Distributor

RF design amp FPGA (Controls Acquisitionshellip) on the same board

12122013 LIU meeting 8

JLollierou JNoirejan GHagmannGHagmann

VME Cards

200MHZ Quadrupler

12122013 LIU meeting 9

RF Function generator

MNaon TLevens GHagmann

GHagmann

12122013 LIU meeting 10

3rd HiLumi LHC-LARP

SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits

RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz

4x

LO Distribution

2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)

SRAM 2x8 Mbyte for diagnostics

VME P1 backplane

for slow controlsread

out

Dedicated backplane (P2)

bull Power Supplybull Clocksbull Interlocksbull hellip

Xilinx Virtex-5 SXT

G Hagmann BE-RF-FBdesigner

Cavity Loops v1

Module Name Status 122012 Status 122013 Software

Linux Front-end (CPU)

Installed Installed NR

CTRV (timing) Installed Installed OK

CMM(Crate Management)

Installed Installed OK

WBS(Wide Band Switch)

LHC Spares available LHC Spares available -

RFFG(Function generator)

under design Installed OK

SwitchampLimit Proto V2 under test V3 pre-series in prod From L4

Clock Distributor Proto V2 under test Proto V3 under test From L4

200MHz Quadrupler Proto V1 in prod V2 in prod NR

Cavity Loops(RF Feedback)

Under design V1 available From L4

Veto Sum Under specification Under specification -

Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR

Status

12122013 LIU meeting 11

Cavity Loop IQ demodulationTWC 800 MHz Frequencies

LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz

Fs

12122013 LIU meeting 12

Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits

The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS

Fine delay(1 Turn)

RF Function Receiver(VoltagePhase offset Setpoint)

Longitudinal Damper(From Beam Control Optical Gbit link)

Ref Phase from 200MHz Cavity Σ

Comb filter(Beam synchronous

clock)

Cavity filter(Absolute Cavity

response)

Feed forward(Beam synch clock)

Polar Loop

In-situ Observation

ampBBNANoise

(Blow-up)

RF Modulator(Single side band Transmitter)

12122013 LIU meeting 13

Ref Phase 200MHz Cavity Σ + setPoint

Comb filter=gt Gain plusmn n∙frev plusmn m∙fs

Cavity filter=gt Sign Inversion

cavity zeros

FiFo1T-delay

NCOupampdown Modulation

RF Modulator

TWC 200 MHz Phase ΣφsetPoint

4x TWC200 Σ

TWC800

Bunch lengthening Bunch shortening

12122013 LIU meeting 14

TWC200 Σ

Filters (implementation)

Beat frequency computation (from pre-defined function)

Downup modulation

12122013 LIU meeting 15

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

New 800 MHz System (VME)

LL Cavity 1 LL Cavity 2

12122013 LIU meeting 6

LL Cavity 1 LL Cavity 2LL Common

New 800 MHz System (VME)

RFFGCMM SwitchampLimitCavity Loops 200MHZ

Quadrupler

Clock Distributor

Linux FrontEnd CTRV

VME

bus

(A24

D16

)R

F Lo

wLe

vel

Bac

kpla

ne

12122013 LIU meeting 7

VME Cards

Switch amp Limit Clock Distributor

RF design amp FPGA (Controls Acquisitionshellip) on the same board

12122013 LIU meeting 8

JLollierou JNoirejan GHagmannGHagmann

VME Cards

200MHZ Quadrupler

12122013 LIU meeting 9

RF Function generator

MNaon TLevens GHagmann

GHagmann

12122013 LIU meeting 10

3rd HiLumi LHC-LARP

SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits

RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz

4x

LO Distribution

2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)

SRAM 2x8 Mbyte for diagnostics

VME P1 backplane

for slow controlsread

out

Dedicated backplane (P2)

bull Power Supplybull Clocksbull Interlocksbull hellip

Xilinx Virtex-5 SXT

G Hagmann BE-RF-FBdesigner

Cavity Loops v1

Module Name Status 122012 Status 122013 Software

Linux Front-end (CPU)

Installed Installed NR

CTRV (timing) Installed Installed OK

CMM(Crate Management)

Installed Installed OK

WBS(Wide Band Switch)

LHC Spares available LHC Spares available -

RFFG(Function generator)

under design Installed OK

SwitchampLimit Proto V2 under test V3 pre-series in prod From L4

Clock Distributor Proto V2 under test Proto V3 under test From L4

200MHz Quadrupler Proto V1 in prod V2 in prod NR

Cavity Loops(RF Feedback)

Under design V1 available From L4

Veto Sum Under specification Under specification -

Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR

Status

12122013 LIU meeting 11

Cavity Loop IQ demodulationTWC 800 MHz Frequencies

LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz

Fs

12122013 LIU meeting 12

Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits

The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS

Fine delay(1 Turn)

RF Function Receiver(VoltagePhase offset Setpoint)

Longitudinal Damper(From Beam Control Optical Gbit link)

Ref Phase from 200MHz Cavity Σ

Comb filter(Beam synchronous

clock)

Cavity filter(Absolute Cavity

response)

Feed forward(Beam synch clock)

Polar Loop

In-situ Observation

ampBBNANoise

(Blow-up)

RF Modulator(Single side band Transmitter)

12122013 LIU meeting 13

Ref Phase 200MHz Cavity Σ + setPoint

Comb filter=gt Gain plusmn n∙frev plusmn m∙fs

Cavity filter=gt Sign Inversion

cavity zeros

FiFo1T-delay

NCOupampdown Modulation

RF Modulator

TWC 200 MHz Phase ΣφsetPoint

4x TWC200 Σ

TWC800

Bunch lengthening Bunch shortening

12122013 LIU meeting 14

TWC200 Σ

Filters (implementation)

Beat frequency computation (from pre-defined function)

Downup modulation

12122013 LIU meeting 15

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

New 800 MHz System (VME)

RFFGCMM SwitchampLimitCavity Loops 200MHZ

Quadrupler

Clock Distributor

Linux FrontEnd CTRV

VME

bus

(A24

D16

)R

F Lo

wLe

vel

Bac

kpla

ne

12122013 LIU meeting 7

VME Cards

Switch amp Limit Clock Distributor

RF design amp FPGA (Controls Acquisitionshellip) on the same board

12122013 LIU meeting 8

JLollierou JNoirejan GHagmannGHagmann

VME Cards

200MHZ Quadrupler

12122013 LIU meeting 9

RF Function generator

MNaon TLevens GHagmann

GHagmann

12122013 LIU meeting 10

3rd HiLumi LHC-LARP

SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits

RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz

4x

LO Distribution

2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)

SRAM 2x8 Mbyte for diagnostics

VME P1 backplane

for slow controlsread

out

Dedicated backplane (P2)

bull Power Supplybull Clocksbull Interlocksbull hellip

Xilinx Virtex-5 SXT

G Hagmann BE-RF-FBdesigner

Cavity Loops v1

Module Name Status 122012 Status 122013 Software

Linux Front-end (CPU)

Installed Installed NR

CTRV (timing) Installed Installed OK

CMM(Crate Management)

Installed Installed OK

WBS(Wide Band Switch)

LHC Spares available LHC Spares available -

RFFG(Function generator)

under design Installed OK

SwitchampLimit Proto V2 under test V3 pre-series in prod From L4

Clock Distributor Proto V2 under test Proto V3 under test From L4

200MHz Quadrupler Proto V1 in prod V2 in prod NR

Cavity Loops(RF Feedback)

Under design V1 available From L4

Veto Sum Under specification Under specification -

Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR

Status

12122013 LIU meeting 11

Cavity Loop IQ demodulationTWC 800 MHz Frequencies

LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz

Fs

12122013 LIU meeting 12

Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits

The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS

Fine delay(1 Turn)

RF Function Receiver(VoltagePhase offset Setpoint)

Longitudinal Damper(From Beam Control Optical Gbit link)

Ref Phase from 200MHz Cavity Σ

Comb filter(Beam synchronous

clock)

Cavity filter(Absolute Cavity

response)

Feed forward(Beam synch clock)

Polar Loop

In-situ Observation

ampBBNANoise

(Blow-up)

RF Modulator(Single side band Transmitter)

12122013 LIU meeting 13

Ref Phase 200MHz Cavity Σ + setPoint

Comb filter=gt Gain plusmn n∙frev plusmn m∙fs

Cavity filter=gt Sign Inversion

cavity zeros

FiFo1T-delay

NCOupampdown Modulation

RF Modulator

TWC 200 MHz Phase ΣφsetPoint

4x TWC200 Σ

TWC800

Bunch lengthening Bunch shortening

12122013 LIU meeting 14

TWC200 Σ

Filters (implementation)

Beat frequency computation (from pre-defined function)

Downup modulation

12122013 LIU meeting 15

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

VME Cards

Switch amp Limit Clock Distributor

RF design amp FPGA (Controls Acquisitionshellip) on the same board

12122013 LIU meeting 8

JLollierou JNoirejan GHagmannGHagmann

VME Cards

200MHZ Quadrupler

12122013 LIU meeting 9

RF Function generator

MNaon TLevens GHagmann

GHagmann

12122013 LIU meeting 10

3rd HiLumi LHC-LARP

SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits

RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz

4x

LO Distribution

2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)

SRAM 2x8 Mbyte for diagnostics

VME P1 backplane

for slow controlsread

out

Dedicated backplane (P2)

bull Power Supplybull Clocksbull Interlocksbull hellip

Xilinx Virtex-5 SXT

G Hagmann BE-RF-FBdesigner

Cavity Loops v1

Module Name Status 122012 Status 122013 Software

Linux Front-end (CPU)

Installed Installed NR

CTRV (timing) Installed Installed OK

CMM(Crate Management)

Installed Installed OK

WBS(Wide Band Switch)

LHC Spares available LHC Spares available -

RFFG(Function generator)

under design Installed OK

SwitchampLimit Proto V2 under test V3 pre-series in prod From L4

Clock Distributor Proto V2 under test Proto V3 under test From L4

200MHz Quadrupler Proto V1 in prod V2 in prod NR

Cavity Loops(RF Feedback)

Under design V1 available From L4

Veto Sum Under specification Under specification -

Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR

Status

12122013 LIU meeting 11

Cavity Loop IQ demodulationTWC 800 MHz Frequencies

LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz

Fs

12122013 LIU meeting 12

Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits

The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS

Fine delay(1 Turn)

RF Function Receiver(VoltagePhase offset Setpoint)

Longitudinal Damper(From Beam Control Optical Gbit link)

Ref Phase from 200MHz Cavity Σ

Comb filter(Beam synchronous

clock)

Cavity filter(Absolute Cavity

response)

Feed forward(Beam synch clock)

Polar Loop

In-situ Observation

ampBBNANoise

(Blow-up)

RF Modulator(Single side band Transmitter)

12122013 LIU meeting 13

Ref Phase 200MHz Cavity Σ + setPoint

Comb filter=gt Gain plusmn n∙frev plusmn m∙fs

Cavity filter=gt Sign Inversion

cavity zeros

FiFo1T-delay

NCOupampdown Modulation

RF Modulator

TWC 200 MHz Phase ΣφsetPoint

4x TWC200 Σ

TWC800

Bunch lengthening Bunch shortening

12122013 LIU meeting 14

TWC200 Σ

Filters (implementation)

Beat frequency computation (from pre-defined function)

Downup modulation

12122013 LIU meeting 15

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

VME Cards

200MHZ Quadrupler

12122013 LIU meeting 9

RF Function generator

MNaon TLevens GHagmann

GHagmann

12122013 LIU meeting 10

3rd HiLumi LHC-LARP

SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits

RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz

4x

LO Distribution

2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)

SRAM 2x8 Mbyte for diagnostics

VME P1 backplane

for slow controlsread

out

Dedicated backplane (P2)

bull Power Supplybull Clocksbull Interlocksbull hellip

Xilinx Virtex-5 SXT

G Hagmann BE-RF-FBdesigner

Cavity Loops v1

Module Name Status 122012 Status 122013 Software

Linux Front-end (CPU)

Installed Installed NR

CTRV (timing) Installed Installed OK

CMM(Crate Management)

Installed Installed OK

WBS(Wide Band Switch)

LHC Spares available LHC Spares available -

RFFG(Function generator)

under design Installed OK

SwitchampLimit Proto V2 under test V3 pre-series in prod From L4

Clock Distributor Proto V2 under test Proto V3 under test From L4

200MHz Quadrupler Proto V1 in prod V2 in prod NR

Cavity Loops(RF Feedback)

Under design V1 available From L4

Veto Sum Under specification Under specification -

Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR

Status

12122013 LIU meeting 11

Cavity Loop IQ demodulationTWC 800 MHz Frequencies

LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz

Fs

12122013 LIU meeting 12

Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits

The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS

Fine delay(1 Turn)

RF Function Receiver(VoltagePhase offset Setpoint)

Longitudinal Damper(From Beam Control Optical Gbit link)

Ref Phase from 200MHz Cavity Σ

Comb filter(Beam synchronous

clock)

Cavity filter(Absolute Cavity

response)

Feed forward(Beam synch clock)

Polar Loop

In-situ Observation

ampBBNANoise

(Blow-up)

RF Modulator(Single side band Transmitter)

12122013 LIU meeting 13

Ref Phase 200MHz Cavity Σ + setPoint

Comb filter=gt Gain plusmn n∙frev plusmn m∙fs

Cavity filter=gt Sign Inversion

cavity zeros

FiFo1T-delay

NCOupampdown Modulation

RF Modulator

TWC 200 MHz Phase ΣφsetPoint

4x TWC200 Σ

TWC800

Bunch lengthening Bunch shortening

12122013 LIU meeting 14

TWC200 Σ

Filters (implementation)

Beat frequency computation (from pre-defined function)

Downup modulation

12122013 LIU meeting 15

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

12122013 LIU meeting 10

3rd HiLumi LHC-LARP

SSB ModulatorIF (I amp Q) asymp25MHzDual TxDac 16 bits

RF DemodulatorRFampLO mixingIF asymp25MHz14 bits ADCFs=4IF asymp100MHz

4x

LO Distribution

2 x Duplex Optical Serial Links2 in amp 2 out2Gbitss(le32Gbitss)

SRAM 2x8 Mbyte for diagnostics

VME P1 backplane

for slow controlsread

out

Dedicated backplane (P2)

bull Power Supplybull Clocksbull Interlocksbull hellip

Xilinx Virtex-5 SXT

G Hagmann BE-RF-FBdesigner

Cavity Loops v1

Module Name Status 122012 Status 122013 Software

Linux Front-end (CPU)

Installed Installed NR

CTRV (timing) Installed Installed OK

CMM(Crate Management)

Installed Installed OK

WBS(Wide Band Switch)

LHC Spares available LHC Spares available -

RFFG(Function generator)

under design Installed OK

SwitchampLimit Proto V2 under test V3 pre-series in prod From L4

Clock Distributor Proto V2 under test Proto V3 under test From L4

200MHz Quadrupler Proto V1 in prod V2 in prod NR

Cavity Loops(RF Feedback)

Under design V1 available From L4

Veto Sum Under specification Under specification -

Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR

Status

12122013 LIU meeting 11

Cavity Loop IQ demodulationTWC 800 MHz Frequencies

LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz

Fs

12122013 LIU meeting 12

Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits

The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS

Fine delay(1 Turn)

RF Function Receiver(VoltagePhase offset Setpoint)

Longitudinal Damper(From Beam Control Optical Gbit link)

Ref Phase from 200MHz Cavity Σ

Comb filter(Beam synchronous

clock)

Cavity filter(Absolute Cavity

response)

Feed forward(Beam synch clock)

Polar Loop

In-situ Observation

ampBBNANoise

(Blow-up)

RF Modulator(Single side band Transmitter)

12122013 LIU meeting 13

Ref Phase 200MHz Cavity Σ + setPoint

Comb filter=gt Gain plusmn n∙frev plusmn m∙fs

Cavity filter=gt Sign Inversion

cavity zeros

FiFo1T-delay

NCOupampdown Modulation

RF Modulator

TWC 200 MHz Phase ΣφsetPoint

4x TWC200 Σ

TWC800

Bunch lengthening Bunch shortening

12122013 LIU meeting 14

TWC200 Σ

Filters (implementation)

Beat frequency computation (from pre-defined function)

Downup modulation

12122013 LIU meeting 15

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

Module Name Status 122012 Status 122013 Software

Linux Front-end (CPU)

Installed Installed NR

CTRV (timing) Installed Installed OK

CMM(Crate Management)

Installed Installed OK

WBS(Wide Band Switch)

LHC Spares available LHC Spares available -

RFFG(Function generator)

under design Installed OK

SwitchampLimit Proto V2 under test V3 pre-series in prod From L4

Clock Distributor Proto V2 under test Proto V3 under test From L4

200MHz Quadrupler Proto V1 in prod V2 in prod NR

Cavity Loops(RF Feedback)

Under design V1 available From L4

Veto Sum Under specification Under specification -

Antenna Vector Sum under design Proto ldquoVector modrdquo under test NR

Status

12122013 LIU meeting 11

Cavity Loop IQ demodulationTWC 800 MHz Frequencies

LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz

Fs

12122013 LIU meeting 12

Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits

The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS

Fine delay(1 Turn)

RF Function Receiver(VoltagePhase offset Setpoint)

Longitudinal Damper(From Beam Control Optical Gbit link)

Ref Phase from 200MHz Cavity Σ

Comb filter(Beam synchronous

clock)

Cavity filter(Absolute Cavity

response)

Feed forward(Beam synch clock)

Polar Loop

In-situ Observation

ampBBNANoise

(Blow-up)

RF Modulator(Single side band Transmitter)

12122013 LIU meeting 13

Ref Phase 200MHz Cavity Σ + setPoint

Comb filter=gt Gain plusmn n∙frev plusmn m∙fs

Cavity filter=gt Sign Inversion

cavity zeros

FiFo1T-delay

NCOupampdown Modulation

RF Modulator

TWC 200 MHz Phase ΣφsetPoint

4x TWC200 Σ

TWC800

Bunch lengthening Bunch shortening

12122013 LIU meeting 14

TWC200 Σ

Filters (implementation)

Beat frequency computation (from pre-defined function)

Downup modulation

12122013 LIU meeting 15

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

Cavity Loop IQ demodulationTWC 800 MHz Frequencies

LO = 318 Frf200 asymp 775 MHzFs = Frf200 2 asymp 100 MHzFif = Fs4 asymp 25 MHz

Fs

12122013 LIU meeting 12

Acquisition 14Bits 100MSPS=gt ENOB asymp 11bits (12MHz)=gt Channels crosstalk lt 11bits

The 800 MHz RF signals (waveguide coupler or cavity sum) are mixed down to a 25 MHz RF using a 775 MHz LO The IF is then sampled at 100 MSPS

Fine delay(1 Turn)

RF Function Receiver(VoltagePhase offset Setpoint)

Longitudinal Damper(From Beam Control Optical Gbit link)

Ref Phase from 200MHz Cavity Σ

Comb filter(Beam synchronous

clock)

Cavity filter(Absolute Cavity

response)

Feed forward(Beam synch clock)

Polar Loop

In-situ Observation

ampBBNANoise

(Blow-up)

RF Modulator(Single side band Transmitter)

12122013 LIU meeting 13

Ref Phase 200MHz Cavity Σ + setPoint

Comb filter=gt Gain plusmn n∙frev plusmn m∙fs

Cavity filter=gt Sign Inversion

cavity zeros

FiFo1T-delay

NCOupampdown Modulation

RF Modulator

TWC 200 MHz Phase ΣφsetPoint

4x TWC200 Σ

TWC800

Bunch lengthening Bunch shortening

12122013 LIU meeting 14

TWC200 Σ

Filters (implementation)

Beat frequency computation (from pre-defined function)

Downup modulation

12122013 LIU meeting 15

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

Fine delay(1 Turn)

RF Function Receiver(VoltagePhase offset Setpoint)

Longitudinal Damper(From Beam Control Optical Gbit link)

Ref Phase from 200MHz Cavity Σ

Comb filter(Beam synchronous

clock)

Cavity filter(Absolute Cavity

response)

Feed forward(Beam synch clock)

Polar Loop

In-situ Observation

ampBBNANoise

(Blow-up)

RF Modulator(Single side band Transmitter)

12122013 LIU meeting 13

Ref Phase 200MHz Cavity Σ + setPoint

Comb filter=gt Gain plusmn n∙frev plusmn m∙fs

Cavity filter=gt Sign Inversion

cavity zeros

FiFo1T-delay

NCOupampdown Modulation

RF Modulator

TWC 200 MHz Phase ΣφsetPoint

4x TWC200 Σ

TWC800

Bunch lengthening Bunch shortening

12122013 LIU meeting 14

TWC200 Σ

Filters (implementation)

Beat frequency computation (from pre-defined function)

Downup modulation

12122013 LIU meeting 15

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

TWC 200 MHz Phase ΣφsetPoint

4x TWC200 Σ

TWC800

Bunch lengthening Bunch shortening

12122013 LIU meeting 14

TWC200 Σ

Filters (implementation)

Beat frequency computation (from pre-defined function)

Downup modulation

12122013 LIU meeting 15

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

Filters (implementation)

Beat frequency computation (from pre-defined function)

Downup modulation

12122013 LIU meeting 15

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

Mid-1980s Comb filter12122013 LIU meeting 16

bull The OTFB must have large gain on the exact revolution frequency sidebands (fRF kmiddotfrev) to fully compensate the transient beam loading The result will be a precise amplitudephase ratio of 200-800 MHz RF for all bunches

bull The OTFB must also have gain on the synchrotron sidebands (fRF kmiddotfrev mmiddotfs) to reduce the real part of the effective cavity impedance The result will be an increased threshold for longitudinal coupled-bunch instability We aim at covering dipole mode (m=1) with full gain and some gain for the quadrupole mode (m=2)

bull The synchrotron frequency range is bull LHC 25ns Q20 fs lt 1 kHzbull Fixed target Q26 fs lt 14 kHzbull LHC ion 12inj Q20 fs lt 22 kHz

bull With the classic simple IIR filter the maximum gain G is inversely proportional to the bandwidth (around the revolution frequency lines)

bull The required minimum 2 kHz -3 dB BW results in a maximum gain of 2 linear Not very impressive

11

with

NN

ck

rev

aH z G za z

fNf

3 13

dB

rev

fGf

p Conclusion The simple IIR filter cannot be used

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

A Modern Comb filter12122013 LIU meeting 17

bull Step1 Decimation by R=5 () -gt 20 MSPSbull Step2 FIR structure at 20 MSPS

bull Step3 Interpolating LPF

119867119888119900119898119887 (119911 )=sum119899=0

119871minus1

119887 ∙119911minus119899lowast 119873 119873=119891 119888119897119896

119877 ∙ 119891 119903119890119907

119867 119897119901 (119911)=sum119899=0

119875minus 1

119887119897119901 ∙ 119911minus119899

FIFO N=462

The gain and BW can now be defined independently at the expense of filter complexity For example G=17 (25 dB) plusmn3 kHz BW in the above design (15 taps)

36 dB stopband attenuation

6 kHz 2-sided BW around the frev lines

8 MHz single-sided -3 dB BW

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

Cavity filter

bull The cavity impedance is real-valued Its sign flips at multiples of 32 MHz frequency

bull We will compensate this with an all-pass filter with zeros at these frequencies

bull This filter will be implemented in the FPGA after the RF synchronous demodulation but its response must not follow the ramping RF frequency (almost 2 MHz drift at 800 MHz for FT beams)

Freq

Fcav800888MHz

~32MHz

Frf flat top~8016MHz

∆f=+071MHz

Frf flat botom~7998MHz

∆f=-112MHz

12122013 LIU meeting 18

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

Cavity filter (in baseband)bull The Filter is implemented with digital circuitry operated with a beam synchronous

clockbull We compensate this by

1 down modulating the antenna signal by the beat frequency (∆f=Frf ndash Fcav) 2 filtering with beam synchronous clock3 Up modulating

∆f

F

down modulation with ∆f

F

FilteringBefore Filtering

F

Up modulation with ∆f

∆fAfter Filtering

12122013 LIU meeting 19

∆fRF200asymp 450 KHz ∆fRF800 = 4∙∆fRF800 asymp 18MHz = ∆fTHORN 57 wrt to 1st zeros (314MHz)

But the zeros still move (negligible) ~314∙045200 asymp 7kHz ( = 023)A candidate sign-flipping filter

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

LIU meeting 20

RF ON-OFF Modulationbull The generation of harmonically related clocks for demodulation (LO)

and sampling require a stable 200 MHz reference locked to the varying revolution frequency during the cycle Frequency Program output

bull Modulation of the 800 MHz can be applied at the set-point level

bull The ON-OFF modulation of the 200 MHz will require some additional treatment to extract 200 MHz phase in CavLoop module Manageable

12122013

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

LIU meeting 21

Operation with Ions (preliminary)bull We could use the 200 MHz RF-AVG (= 4620 frev) as reference for

generation of the clocks

bull Compensation of transient beam loading would work correctly with fixed frequency acceleration as it depends on the revolution period only

bull The tracking of the 200 MHz phase must be studied

12122013

Sawtooth

Frf200Frf avg (ions)

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

LIU meeting 22

Planningbull The two cavities are equipped with antenna on all cells

bull 1 antenna per cellbull The Antenna Summing network is being designed

bull Help from D Valuchbull Prototype beginning of 2014

bull Electronics pre-series amp prototype are available or being produced bull Tests beginning 2014

bull We are developing the following firmware functionalities for start-upbull 1T-delay feedbackbull 200MHz cavity sum phase extractionbull Polar loop (if time allows)

bull The design will be adapted according to these first resultsbull We would benefit from a period with IOT-Cavity but without beam

during SPS hardware commissioning at start-up

12122013

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

LIU meeting 23

Thank you for your attentionhellip

12122013

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

LIU meeting 24

References[1] D Boussard et al Controls of Strong Beam Loading IEEE Transaction on Nuclear Sciences 1985[2] P Baudrenghien et al Control of strong beam loading Results with beam Chamonix 2001[3] T Mastoridis et al RF system models for the CERN Large Hadron Collider with application to longitudinal dynamics Phys Rev Sp Topics AB 13 102801 2010[4] P Baudrenghien et al The LHC RF System Is it working well enough Chamonix 2011[5] D Boussard Travelling-Wave structures Joint US-Cern-Japan Intl School Tsukuba 1996[6] P Baudrenghien CAS RF 2000 and 2010

12122013

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

LIU meeting 25

Back-Up slides

12122013

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation

CavityLoop Up-modulationRF Modulation SSB 16Bits DACs

12122013 LIU meeting 26

Low phase noise(LO from Agilent E8663B still)

Span 20MHzSFDR gt 100dB

∆ +- 1deg∆G +- 05dB

phase

Gain

• LLRF for the SPS 800 MHz cavities
• Block diagram
• 800 MHz TX-cavity chain
• 800 MHz TX-cavity chain (contrsquod)
• Vector sum
• New 800 MHz System (VME)
• New 800 MHz System (VME) (2)
• VME Cards
• VME Cards (2)
• Slide 10
• Status
• Cavity Loop IQ demodulation
• Slide 13
• TWC 200 MHz Phase Σ
• Filters (implementation)
• Mid-1980s Comb filter
• A Modern Comb filter
• Cavity filter
• Cavity filter (in baseband)
• RF ON-OFF Modulation
• Operation with Ions (preliminary)
• Planning
• Thank you for your attentionhellip
• References
• Back-Up slides
• CavityLoop Up-modulation