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The CBC2 ASIC for 2S Modules at HL-LHC. Davide Braga IOP 2014 Joint HEPP and APP Groups Annual Meeting, Royal Holloway, May 2014. Outline. Tracker upgrade & detector module The CMS Binary Chip (CBC) v.1 & 2 CBC2: architecture & performance CBC2 testing Beam test TID test. - PowerPoint PPT Presentation
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The CBC2 ASIC for
2S Modules at HL-LHC
Davide Braga
IOP 2014 Joint HEPP and APP Groups Annual Meeting, Royal Holloway, May 2014
Outline
•Tracker upgrade & detector module
•The CMS Binary Chip (CBC) v.1 & 2
•CBC2: architecture & performance
•CBC2 testing
• Beam test
• TID test
IOP 2014 MeetingDavide Braga, IC 2
Davide Braga, IC IOP 2014 Meeting 3
Phase-II upgrade of the CMS Strip Tracker
• Baseline design: Barrel+5Endcaps
• Based on 2 module types only
• Provides at the same time:• readout data upon receipt of L1 trigger• trigger data @40MHz (10 trigger hits up to η=2.5)
2S strip-strip double-layers~8400 modules~34M channels~155m2
PS strip-strixel double-layers~7000 modules~230M channels~62m2
IOP 2014 Meeting 4
Basic trigger module concept
Pass Stub Fail
R
f
~200μm
~100μm
~2-4 mm
outer sensor
inner sensor
• High-PT tracks (stubs) can be identified if cluster centre in top layer lies within a
search window in R-Φ (rows)
• pT cut given by: module radius (z), sensor separation and correlation windowDavide Braga, IC
IOP 2014 Meeting 5Davide Braga, IC
4 mm
5 mm
7 m
m
11 m
m
CBC1
CBC2
2 versions have now been produced - both in 130nm CMOS
CBC1 (2011)• 128 wire-bond pads, 50 mm pitch• front end designed for short strips, up to 5 cm
DC coupled, up to 1mA leakage tolerant, both sensor polarities
• binary unsparsified readout• pipeline length 6.4 msec
• chip worked well in lab and test beam• no triggering features
CBC2 (January, 2013) • 254 channels• ~same front end, pipeline, readout approach as CBC1 • bump-bond layout• includes triggering features
CMS Binary Chip (CBC)
IOP 2014 Meeting
rf
beam
offset windowwidth
top layer clusters
bottom layer clusters
zerooffset
Cluster width discrimination (CWD) logic
exclude clusters with hits in >3 neighbouring channelswide clusters not consistent with high pT track
Offset correction & correlation logic
for a cluster in bottom layer, look for correlating cluster occurring in window in top layer
window width controls pT cutstub found if cluster in bottom layer corresponds to cluster within window in top layer
window width programmable up to ± 8 channels
offset defines lateral displacement of window across chipprogrammable up to ± 3 channels
n
n+1
n-1
1/2/3 stripcluster onchannel n
programme clusterwidth to accept
channelcomparator
outputs
CWD logic
Stub finding logic
6Davide Braga, IC
IOP 2014 Meeting 7
CBC2 architecture
pipe. control
FE amp comp. pipeline shift reg.
vth
vth
vth
vth
256 deeppipeline
+32 deepbuffer
testpulse
biasgen.
fastcontrol
slow control
stub
shi
ft re
gist
er
offs
et c
orre
ctio
n &
cor
rela
tion
clus
ter w
idth
di
scrim
inat
ion
1
254 40 MHz diff.clock
signals in blue are single-ended
trig’d data outstub shift reg. O/Ptrigger O/PI2C
254 channels: 127 from each sensor layerchannel mask: block noisy channels from trigger logicCWD logic: exclude wide clusters >3correlation logic: for each cluster in lower layer look for cluster in upper layer windowtrigger output: 1 bit per BX indicates correlation logic found one (or more) stubs triggered data out: unsparsified binary data frame in response to L1 trigger
nearest neighbour signals
T1 triggerfast resettest pulseI2C refresh
4 4 11 11
chan
. m
ask
4 4 11 11
nearest neighbour signals
reset
OR_254
OR_stubs
Ck
Davide Braga, IC
IOP 2014 Meeting 8
CBC2 performance
• All core functionality meets requirements
• Correlation functionality verified with test pulses,cosmics (backup), and in test beam
• Analogue performance close to simulation and specifications
e.g. 1000e noise for 5 cm strips (~8 pF)achievable for total channel power of 350 uW
noise & power vs. external capacitance
nois
e [e
RM
S]
power/chan. [uW
]
external capacitance [pF]
electronsmode
/ measured/ simulation
12001000
800600400200
0121086420
400350300250200150100
100
80
60
40
20
0
num
ber o
f eve
nts
600500400300200
comparator threshold VCTH [mV]
1 fC
8 fC
S-cu
rves
channel offsets tuning
coun
ts
comparator threshold [I2C units]
holesmode
before tuneafter
100
80
60
40
20
0200180160140
M. Raymond
Davide Braga, IC
CBC2 testing activities
Wire-bond CBC2• Useful to develop wafer probe procedures
• X-rays TID testing
2xCBC2 hybrid• Hybrid characterization and chip integration
• Bump-bonded ASICs
• Inter-chip links & logic
Davide Braga, IC IOP 2014 Meeting 9
2xCBC2 mini-module + sensor• Sr-90 source
• Cosmic rays
• Beam Test
IOP 2014 Meeting 10
Pt module beam test at DESY
TOP VIEW: strip direction into page
positron beamlow angular divergence (small angular error)
scintillator scintillator
module #4 on rotation stage
module #3 on fixed assembly
Mimosa26 MAPS (DATURA telescope)
~3 GeV e+
Daturatelescope
planes
pTmodule
• December 2013
• 4 GeV positron beam
• Datura telescope + 2 pT modules (1 rotatable to
simulate B-field effect) + 2 different strip sensors
• Custom control and DAQ
Davide Braga, IC
S. Viret
Davide Braga, IC IOP 2014 Meeting 11
Beam test results
Pt Selection cut: simulation measured efficiency
Other measurements include:
• Study of cluster width
• System noise
• Beam profile
avg. cluster widthvs
angle of incidence
EXP. pT cut: 2.14 GeV/cFIT: pT cut: 2.17 GeV/c σ: 0.1 GeV/c
M.Pesaresi
reconstructed pT cut of r=75cm layer
Incident Angle
Clus
ter W
idth
Total Ionizing Dose test
• First xray irradiation to 10 Mrads
• CBC2 operated continuously during irradiation
• monitored currents, biases, pedestal, noise
• no significant change in performance, moderate
increase in current before annealing
• Next: TID test up to ~50 Mrads
Davide Braga, IC IOP 2014 Meeting 12
Xray tubeCBC2
Bias/readout
IOP 2014 Meeting 13Davide Braga, IC
Milestones so far: CBC2 working to specs
Stub finding logic functioning TID dose irradiation test under way
First prototype version of 2S module extensively tested Beam test at DESY successful Pt selection cut and stub logic demonstrated DAQ working well
Future work:• Continue with 2S module prototyping
(8chip hybrid from CERN)• SEU test of CBC2• CBC3: final prototype version with full stub readout
First results to prove the track-trigger concepta very new idea never before implemented
CMS ambitious plans for a track trigger look promising
Conclusions and Future Work
A. Honma