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This article discusses the data acquisition and electronics for a silicon tracker in the context of the linear collider, including preliminary studies, double and multiple hit rates, sparsification, and power dissipation. It also covers the readout of the Si-tracker and the front-end processing.
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Silicon Tracker Data Acquisition and Electronics for the Linear Collider Jean-Francois Genat LPNHE Universite Pierre et Marie Curie CNRS/IN2P3 On behalf of: Philippe Bailly, Jean-Francois Genat, Herve Lebbolo,Olivier le Dortz and Aurore Savoy Navarro ECFA Linear Collider Workshop, Durham UK, Sept. 3d 2004
Output signals: very preliminary exercise Exercise performed with 3 external layers of a Silicon tracker: Multiplex as much as possible the output signals from the detector At the digitization stage: highly multiplexed A/D scheme
-Detector occupancy: • Outer central region: Preliminary studies: < 1 % • Inner central and forward regions: Preliminary studies: < 10%Work in progress with Geant • - Double & Multiple hit rates: Ambiguities to be estimated: tiling vs long strips • - Sparsification/pedestal substraction: On the detector FE • - Pulse height needed: Cluster centroid to improve position resolution to 7–8µm A 10 bit A/D under construction • - Timing informationIncluded in the FE design. The principle & possible • performances are being studied Paris test bench • - Digital processing for cluster algorithm and fast-track processing algorithm. Under study while designing FE • - Power dissipation studies: Present results do not anticipate a major pb passive (or light) cooling might be achievable. • FE Power cycling The readout of the Si-tracker Jean-Francois Genat, ECFA Linear Collider Workshop, Durham, September 3d 2004
Context All Silicon Tracker envelope: a few 100m2, a few 106 strips Asynchronous events: ~ 1 ms Data taking/pre-processing ~ 200 ms Occupancy: < a few % Jean-Francois Genat, ECFA Linear Collider Workshop, Durham, September 3d 2004
Goals: Low noise preamplifiers Long shaping time Time measurement Very low power dissipation Shared ADC/TDC Digitization @ sparsification Power cycling Compact and transparent Choice of DSμE
S&H: digitization Amplification + long shaping + storage + time tagging Front-end processing (To Trigger) Calibration Control Charge: PA shaper, S&H, Disc ADC Ch # Storage Compaction Time: Disc, Digital delay Time, Charge Counter Readout (From Trigger) Charge 1-45 MIP, S/N~40, Time 1ns Technology: Deep Sub-Micron CMOS UMC 0.18 mm Faster and less 1/f noisy alternative: Silicon-Germanium Jean-Francois Genat, ECFA Linear Collider Workshop, Durham, September 3d 2004
Analog N.B: The time measurement will not be included in the first FE design. It will be firstexperienced on the Lab test bench. CR-RC Shaper (3-5 us) Sample and Hold Input Charge Hold Charge Preamp Cf = 400 fF Discriminators High threshold Digital delay Time Low threshold Jean-Francois Genat, ECFA Linear Collider Workshop, Durham, September 3d 2004
Deep Sub-Micron CMOS 0.18 mm technology Preamp - Shaper - 1-45 MIP - Gain 8 mV/MIP - 195 mW/ch If 100 MIPS needed, just twice preamp power Timing • Two-threshold discriminator • 60 mW ADC - 4 ms conversion time - 10 bits (500 MHz internal clock) - 40 mW/ch Jean-Francois Genat, ECFA Linear Collider Workshop, Durham, September 3d 2004
Performance - Noise: - Preamp + Shaper @ 5 ms shaping time, 50 pF detector (no leak, no bias resistor): simulated 690 e- ENC S/N ~ 40 Gain 8mV/MIP - Power: - Preamp + Shaper + timing Preamp: 85 mW Shaper: 110 mW Timing: 60 mV - Shared ADC/TDC ADC: 40 mW Total: 295 mW/channel Power Switching: If Preamp –Shaper +ADC are running during collisions only: e.g. 1/100 duty cycle and 2 106 channels, then: Total:295 10-6 x 2 106 x 1.3 10-2 =7.7 Watts only ! Jean-Francois Genat, ECFA Linear Collider Workshop, Durham, September 3d 2004
Preamp Linearity 10-3 Linearity better than ± 5‰ Jean-Francois Genat, ECFA Linear Collider Workshop, Durham, September 3d 2004
Shaper response 5 MIP/step Shaper response Gain: 8mV/MIP over 45 MIP Jean-Francois Genat, ECFA Linear Collider Workshop, Durham, September 3d 2004
Noise If 1/f noise shows up at 5 ms shaping, consider Silicon-Germanium technology Jean-Francois Genat, ECFA Linear Collider Workshop, Durham, September 3d 2004
ADC Comparator: Time Walk simulations 10-4 Linearity better than ± 5‰0 Jean-Francois Genat, ECFA Linear Collider Workshop, Durham, September 3d 2004
Digital • - TDC counter • - ADC coding • - Memory • - Zero suppression and lossless data compression • - Calibration management • Tools: • Virtual Silicon Library for UMC 0.18 mm • - I/O pads • - VHDL/Verilog • - Synthesizer interface (Ambit) • Cadence Silicon Ensemble for digital layout • - Merge manually analog and digital cells • Help from Erwin Deumens at IMEC (Leuven) Jean-Francois Genat, ECFA Linear Collider Workshop, Durham, September 3d 2004
Layout 16 analog charge channels: - 60 mm pitch, - I/O pad, preamp, shaper, sample & hold, comparator - Full prototype chip including digital fits in 2.2 mm2 1mm 0.75mm Jean-Francois Genat, ECFA Linear Collider Workshop, Durham, September 3d 2004
Silicon • UMC 0.18 mmEuropractice (Leuven) • Standard 5 x 5 mm2 or 2.2 x 2.2 mm2 (share is possible) • One full analog channel (including I/O) pad is • 60 x750mm2 = .045 mm2 only • Full 128 channels chip may fit in less than 25 mm2 • (SVX4 in TSMC 0.25 is ~60 mm2 for 128 channels • including analog pipe-lines, ADC, I/O) • - Submission at Europractice: next UMC run mid October Jean-Francois Genat, ECFA Linear Collider Workshop, Durham, September 3d 2004
Conclusion Emerging new VLSI technologies: - Silicon Deep Sub Micron CMOS - Silicon-Germanium alternative (incorporate DSM CMOS) allow to implement a highly integrated front end for SiLC that does not degrade the detector resolution, both in time and amplitude within an affordable power and material budget and implement system integration such as data compaction, cluster centroid, fast tracking algorithms Jean-Francois Genat, ECFA Linear Collider Workshop, Durham, September 3d 2004