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October, 2004 CMS Tracker Week 1
APV settings at cold temperatures
Objective:provide recommendations for APV I2C settings for cold operation,
for test beam and eventually CMS
Outline:what are the temperature effects and where do they come from?experimental method used to measure and compensate for T effectsrecommendations from results of measurements on 4 APV TIB module
Mark Raymond, Imperial College
October, 2004 CMS Tracker Week 2
IPREIPCASC
VFP VFS
IPSF ISSFISHA IPSPIMUXIN
VPSP
APV bias settings
all analogue bias currents on chip derived from one masterreference current (provides reference current to bias gen.)
Iref depends on Vt and R (not V250)
but Vt and R have T dependence
as T↓ , Vt ↑ 1mV / OC R ↓ 0.15% / OC
so Iref ↑ (simulation -> 0.233% / OC)
Reference currentcircuit
APV analogue chain
October, 2004 CMS Tracker Week 3
Temperature effects on APV
T reduces -> master Iref increases -> all I2C bias currents increase -> chip power increases
reduce bias currents (I2C parameters beginning with ‘I’) to compensate
simple method: adjust each parameter by same factor and round to nearest integer
Other T effects
T reduces -> µ increases => gm increases => circuit speed increases, pulse shape changes and needs re-tuning
APV gain also depends on R at MUX I/P stage, so gain goes up as T reduces
gain
October, 2004 CMS Tracker Week 4
Experimental setup
VUTRI card
TIB module
environmentalchamber
flushed withnitrogen
October, 2004 CMS Tracker Week 5
Experimental setup
sensor
12
56
Pt100 temperature sensors
peltier
peltier
hybrid
Al plate
hybrid in contact with Al plate (thermal grease)2 peltier elements cool platePt100 sensor measures hybrid temperature (where APVs 3 and 4 would be if 6 chip module)another Pt100 measures Al plate underside temperature
hybrid temp. ~3O > Al plate temp.temperature stability ~ ± 2O
October, 2004 CMS Tracker Week 6
Experimental setup
peltierfan-cooled
heatsink
90Srsource
scintillatorbeneath sensor
Pt100 hybrid in thermalcontact with Al plate
peltier
October, 2004 CMS Tracker Week 7
Method1) wait for environment to stabilise at target hybrid temperature
2) adjust peltier current to fine tune hybrid temperature to target value
3) tune I2C Ibias parameters to get ~ same V250 and V125 currents as for standard values @ +30O
4) tune ISHA to achieve close approx. to 50 ns peak mode pulse shapeaverage of 16 pulse shapes corresponding to one test pulse linepulse shape tuned “by eye”not found necessary to alter VFS setting (or VPSP)
120
100
80
60
40
20
0
ADC
uni
ts
3002001000time [nsec]
+30o
Isha=46
120
100
80
60
40
20
0
3002001000time [nsec]
-20o
Isha=30
+30 -20peakideal CR-RCdecon
October, 2004 CMS Tracker Week 8
Pulse shapes120
80
40
0
ADC
uni
ts
3002001000
+30o
Isha=46
120
80
40
0
ADC
uni
ts
3002001000
+10o
Isha=38
120
80
40
0
3002001000
+20o
Isha=45
120
80
40
0
AD
C u
nits
3002001000[nsec.]
-10o
Isha=30
120
80
40
0
3002001000
0o
Isha=32
120
80
40
0
3002001000[nsec.]
-20o
Isha=30
Pulse shapes for all temperatures aftertuning for correct power and pulse shape
VFS = 70 for all temperatures
ICAL=80 in all cases, but outputsignal amplitude increases as T↓
1.21-20
1.17-10
1.120
1.08+10
1.04+20
1.00+30
relativetest pulse height
dependenceon T
ICAL derived from master ref. butgain also increases as T↓ so twocontributing effects here
October, 2004 CMS Tracker Week 9
400300200100
0
30025020015010050[nsec.]
-20o
400300200100
0
AD
C u
nits
30025020015010050[nsec.]
-10o
400300200100
0
30025020015010050
0o400
300200100
0
AD
C u
nits
30025020015010050
+10o
400300200100
0
30025020015010050
+20o
400300200100
0
AD
C u
nits
30025020015010050
+30o
400300200100
0
250200150100500[nsec.]
-20o
400300200100
0
AD
C u
nits
250200150100500[nsec.]
-10o
400300200100
0
250200150100500
0o400
300200100
0
AD
C u
nits
250200150100500
+10o
400300200100
0
250200150100500
+20o
400300200100
0
AD
C u
nits
250200150100500
+30o
Peak & deconvolution pulse shapesICAL: 0 -> 240 in steps of 40 (1 mip ~ 60 ADC units)
October, 2004 CMS Tracker Week 10
Chip-to-chip variation on this hybrid80
70
60
50
40
30
20
10
0
AD
C u
nits
300250200150100500[nsec]
apv5 apv6 apv2 apv1
80
70
60
50
40
30
20
10
0
AD
C u
nits
300250200150100500[nsec]
apv5 apv6 apv1 apv2
room temperature measurement – hybrid at 30O
same I2C parameters for all 4 chips (including VFS and ISHA)small ICAL response differences here (but absolute value of test charge subject to chip to chip variation)
and small pulse shape differencesbut these chips will have been picked from same wafer (probably same location on wafer)how will pulse shape vary across full production?
-> look at wafer probe data
October, 2004 CMS Tracker Week 11
120100806040200
Lot_5
120100806040200
Lot_3
peak and deconvolution mode pulse shapes are acquiredfor every chip at wafer test time (for same I2C parameters)
example data here (presented at LECC’02) for lots 1 to 5(see http://www.hep.ph.ic.ac.uk/~dmray/pdffiles/APV_LECC02_HEP.pdf)
plots show pulse shapes for all KGD normalised to max. pulse height
120100806040200
Lot_1
120100806040200
Lot_3
120100806040200
Lot_2
120100806040200
Lot_5
120100806040200
Lot_4
120100806040200
Lot_1
120100806040200
Lot_2
120100806040200
Lot_4
Peak DeconvolutionLot 1 Lot 1
Lot 4
Lot 5Lot 3
Lot 2
Lot 3 Lot 5
Lot 2 Lot 4
Wafer to wafer pulse shape variation
conclusion
one set of start-up I2C parameters will suit all chips, at least for a particular module type
fine tuning can then followlater
October, 2004 CMS Tracker Week 12
Beta pulse height spectraPeak Mode Deconvolution
90Sr source, sensor HT 250V
strip signal included if neighbour signal < 3 x noise
S/N values quoted for mostprobable signal
500400300200100
0
coun
ts
200150100500
+30o
pk ch 57S/N=25.7
400300200100
0
coun
ts
200150100500
+30o
pk ch 56S/N=16.6
400300200100
0200150100500
ADC units
-20o
pk ch 61S/N=29.0
300
200
100
0200150100500
ADC units
-20o
pk ch 60S/N=17.9
best way to measure gain changes with T gain increase, +30 -> -20 = ~ 7% (7.5% expected from gain resistor)S/N increase: ~13% peak mode, ~8% deconvolution
not quite the same but significant errors here (statistics and details of pulse shape)
October, 2004 CMS Tracker Week 13
Beta pulse height spectra
400300200100
0200150100500
ADC units
-20o
pk ch 61S/N=29.0
400300200100
0
coun
ts
200150100500ADC units
-10o
pk ch 59S/N=28.1
500400300200100
0200150100500
0o
pk ch 58S/N=27.6
500400300200100
0
coun
ts
200150100500
+10o
pk ch 57S/N=26.4
500400300200100
0200150100500
+20o
pk ch 57S/N=24.6
500400300200100
0
coun
ts
200150100500
+30o
pk ch 57S/N=25.7
300
200
100
0200150100500
ADC units
-20o
pk ch 60S/N=17.9
250200150100500
coun
ts
200150100500ADC units
-10o
pk ch 58S/N=18.1
300
200
100
0200150100500
0o
pk ch 56S/N=17.8
200150100500
coun
ts
200150100500
+10o
pk ch 55S/N=16.8
250200150100500
200150100500
+20o
pk ch 57S/N=16.6
400300200100
0
coun
ts
200150100500
+30o
pk ch 56S/N=16.6
Peak Mode Deconvolution
October, 2004 CMS Tracker Week 14
Recommended I2C parameters vs. T
368364374368370366power/APV
147514551479147314801465total power[mW/module]
707070707070VFS
303032384546ISHA
434343434343VPSP
303030303030VFP
303032333434IMUXIN
484852535455IPSP
303032333434ISSF
303032333434IPSF
454549495152IPCASC
858592939698IPRE
- 20O- 10O0O+ 10O+ 20O+ 30O all bias current params (those starting with ‘I’) adjusted by same factorto achieve ~ same total module power at each temperature
over ~ 10O range power variation small(~ few %) so not necessary to re-tuneparameters for variations at this level
slight over-adjustment between 0 -> -10so no further adjustment needed for -20
power/APV = total power / 4 but this alsoincludes APVMUX, DCU and PLL power(not possible to separate out)
recommend values in –10O column for CMS operation
Note: this doesn’t apply to VPSP, ISHAand VFS. ISHA and VFS will depend on sensor type and some chip to chip variationcan also be expected
October, 2004 CMS Tracker Week 15
Digital header amplitudedigital header (and tick mark) amplitude varies with T because levels are set by current ref. circuit similar to that for bias generator
1.111.091.071.051.021.00relative dig. head amplitude
- 20O- 10O0O+ 10O+ 20O+ 30O
dig.headamp.
October, 2004 CMS Tracker Week 16
analogue baseline
VPSP setting
VPSP setting adjusts analogue baseline position
works by introducing DC voltage offset at APSP O/P which in turn produces DC offset current flowing in the MUXstages
choice of VPSP for this studyno major movement in analogue baseline observed with temperaturesame value (43) used throughout
sets baseline at ~ 25% relative to dig. head amp.allows plenty of room for signals and negativeCM excursions
note: power penalty if set higher than necessarye.g. ~ 7% power increase if move from 25%to 50% level
0
100%
18001600140012001000800600400200
0
tota
l mod
ule
pow
er [m
W]
70 60 50 40 30 20 10 0
VPSP setting (decimal)
9080706050403020100
baseline pos'n [% of dig. am
p.]
50%
module powerbaseline pos’n
October, 2004 CMS Tracker Week 17
What happens if no I2C change with T?
100
80
60
40
20
0
AD
C u
nits
250200150100500time [nsec]
30 20 10 0 -10 -20
100
80
60
40
20
0
AD
C u
nits
30025020015010050
30 20 10 0 -10 -20
standard I2C settings used for all temperatures
module power increases by ~ 10% (+30 -> - 20)
test pulse amplitude increases
gm increase in shaper and preamp -> rise-timefaster as T decreases
deconvolution pulse shape sensitive torise-time
October, 2004 CMS Tracker Week 18
T measurement using DCU
DCU ADC value shows linear dependenceon hybrid temperature measured with Pt100
9.65 slope value similar to 9.22 quoted inDCU manual
clearly no problem to use DCU to measurehybrid temp. if calibration factor known
2700
2600
2500
2400
2300
2200
DC
U A
DC
val
ue
3020100-10-20hybrid temp. [deg.C]
2412+9.65/deg.
October, 2004 CMS Tracker Week 19
Summaryrecommendations provided for APV I2C settings for low temperature operation
based on studies of 4 chip TIB modulehybrid temperature used as reference
provides starting point for module operation but free parameters still existVPSP sets analogue baseline. remember power penalty if set highISHA/VFS tune pulse shape
~ some chip to chip variationwill be different for different sensor types
results here consistent with previous studies on single chipspresented CMS week in Catania (June 2001, E. Noah)
note available with more details:http://www.hep.ph.ic.ac.uk/~dmray/pdffiles/cold_APV_params.pdf
(preliminary version already circulated)
ongoing workverify parameter choice for 6 chip TIB module – expect to be same as 4 chip versionlook at other module types – old TOB module available
70VFS
30ISHA
43VPSP
30VFP
30IMUXIN
48IPSP
30ISSF
30IPSF
45IPCASC
85IPRE
- 10O
October, 2004 CMS Tracker Week 20
Supply currents vs. T if no I2C change
500
400
300
200
mod
ule
curre
nt [m
A]
403020100-10-20
hybrid temperature [ oC]
I125 I250 total I250 digital only I250 analog only
standard I2C settings used for all temperatures
I125 shows 16% increase, +40 -> -20(close to 14% simulated)
I250 total includes digital and analogue
I250 digital only measured by switching biasoff in mode registers
small ~ 3.5% increase, +40 -> -20
I250 analogue only = I250 total – I250 digital only~ 21% increase (> I125 but probably includessome contribution from analogue baseline shift)
module power+40 -> -201.43 W -> 1.56 W ~ 10% increase
but extra power also dissipated in cables