1. Valerio Re, Massimo Manghisoni Università di Bergamo and INFN, Pavia, Italy Jim Hoff, Abderrezak Mekkaoui, Raymond Yarema Fermi National Accelerator Laboratory Lodovico Ratti Università di Pavia and INFN, Pavia, Italy IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors

2. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” The FSSR2 chip  Mixed-signal integrated circuit for the readout of silicon strip detectors  Final step of R&D effort begun with the design of the prototype chip FSSR  TSMC 0.25 µm CMOS technology with enclosed NMOS for radiation tolerance  128 analog channels, address, time, and magnitude information for all hits  Fast, self-triggered readout architecture with no analog storage, very similar to the FPIX2 chip (front-end for pixels in the BTeV experiment)  Designed for the BTeV Forward Silicon Tracker, FSSR2 is suitable for a wide range of applications with microstrip detectors  Mixed-signal integrated circuit for the readout of silicon strip detectors  Final step of R&D effort begun with the design of the prototype chip FSSR  TSMC 0.25 µm CMOS technology with enclosed NMOS for radiation tolerance  128 analog channels, address, time, and magnitude information for all hits  Fast, self-triggered readout architecture with no analog storage, very similar to the FPIX2 chip (front-end for pixels in the BTeV experiment)  Designed for the BTeV Forward Silicon Tracker, FSSR2 is suitable for a wide range of applications with microstrip detectors

3. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” Major requirements   Data driven architecture – no trigger   Operation at 132 ns (2% strip occupancy), 264, or 396 ns (6 % strip occupancy) beam crossing   Tolerance to total ionizing dose (5 Mrad) and single event effects (SEU)   Equivalent Noise Charge (ENC) < 1000 e rms @ C D = 20 pF   Threshold dispersion < 500 e rms   Power < 4 mW/channel

4. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” The FSSR2 chip 7.5 mm x 5 mm, input pads with 50  m pitch Data output Interface Programming Interface Pixel Core LogicFront-End

5. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” FSSR2 block diagram FSSR2 Core – –128 analog channels – –16 sets of logic, each handling 8 channels – –Core logic with BCO counter (time stamp) Programming Interface (slow control) – –Programmable registers – –DACs Data Output Interface – –Communicates with core logic – –Formats data output – –Same as BTeV FPIX2 chip FSSR2 Core – –128 analog channels – –16 sets of logic, each handling 8 channels – –Core logic with BCO counter (time stamp) Programming Interface (slow control) – –Programmable registers – –DACs Data Output Interface – –Communicates with core logic – –Formats data output – –Same as BTeV FPIX2 chip

6. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” Analog channels

7. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” Analog channels Preamplifier – –NMOS input device, W/L = 1500/0.45, I D = 500  A – –Programmable charge sensitivity Integrator and shaper – –Unipolar 2 nd order semigaussian shaper – –Four programmable shaping times (65, 85, 100, 125 nsec) Base Line Restorer – –Cancellation of the baseline shift due to the tail in the shaper output signal – –The BLR is selectable, so that it can be used only when signal occupancy is high Discriminator – –Binary information (hit / no hit) – –Programmable differential threshold (chip wide) 3 bit Flash ADC – –Pulse amplitude information for detector monitoring and calibration Preamplifier – –NMOS input device, W/L = 1500/0.45, I D = 500  A – –Programmable charge sensitivity Integrator and shaper – –Unipolar 2 nd order semigaussian shaper – –Four programmable shaping times (65, 85, 100, 125 nsec) Base Line Restorer – –Cancellation of the baseline shift due to the tail in the shaper output signal – –The BLR is selectable, so that it can be used only when signal occupancy is high Discriminator – –Binary information (hit / no hit) – –Programmable differential threshold (chip wide) 3 bit Flash ADC – –Pulse amplitude information for detector monitoring and calibration

8. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” Digital section  Programming Interface Accepts commands and data from serial input bus Programmable registers hold input values for DACs providing reference currents and voltages to the core (discriminator thresholds, test signal amplitude,…)  Data Output Interface Serializes data from the core and transmits data off chip Programmable number of output LVDS lines (1, 2, 4, 6) Maximum data transmission rate 840 Mb/s Output data word includes 3 bits for ADC pulse amplitude information, 5 bits for the logic set number, 4 bits for strip number and 8 bits for hit BCO number (time stamp)

9. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” Test results The chip is fully functional and meets all specifications Power dissipation is 4 mW/channel The chip has been operated with a 70 MHz readout clock to provide 840 Mb output data rate. Threshold dispersion = 300 e rms (with BLR, high gain setting) ENC = 800 e rms (C D = 20 pF, peaking time = 85 nsec, with BLR)

10. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” Shaper output response Charge sensitivity at shaper output: Low gain: 120 mV/fC High gain: 160 mV/fC

11. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” Baseline restorer

12. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” Equivalent Noise Charge

13. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” Equivalent Noise Charge The BLR improves the threshold dispersion (AC coupling), but increases noise However, ENC is well below the spec value of 1000 e rms at C D = 20 pF.

14. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” Radiation tolerance FSSR prototype   Irradiation with 27 MeV protons to a 1.9x10 13 cm -2 fluence, corresponding to a total ionizing dose of 5 MRad   After irradiation the chip remains fully functional with very little (< 10 %) degradation of critical parameters such as ENC and threshold dispersion FSSR2   Irradiation with 60 Co  -rays to a total ionizing dose of 20 Mrad (no bias applied during irradiation)   Chip fully functional after irradiation; noise and charge sensitivity are not affected   Threshold dispersion with BLR selected increases by about 15 % (remains below the spec value of 500 e rms) FSSR prototype   Irradiation with 27 MeV protons to a 1.9x10 13 cm -2 fluence, corresponding to a total ionizing dose of 5 MRad   After irradiation the chip remains fully functional with very little (< 10 %) degradation of critical parameters such as ENC and threshold dispersion FSSR2   Irradiation with 60 Co  -rays to a total ionizing dose of 20 Mrad (no bias applied during irradiation)   Chip fully functional after irradiation; noise and charge sensitivity are not affected   Threshold dispersion with BLR selected increases by about 15 % (remains below the spec value of 500 e rms)

15. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” Conclusions The 128-channel chip FSSR2 was designed and successfully tested. The device is fully functional and meets demanding specifications in terms of noise and threshold dispersion Because of its low noise, radiation tolerance and high data output bandwidth and of the flexibility provided by the various programmable features, FSSR2 can operate in different experimental environments and applications FSSR2 is being evaluated in view of its possible operation for detector readout in a tracking system providing information to a first level trigger for both fixed target and collider experiments The 128-channel chip FSSR2 was designed and successfully tested. The device is fully functional and meets demanding specifications in terms of noise and threshold dispersion Because of its low noise, radiation tolerance and high data output bandwidth and of the flexibility provided by the various programmable features, FSSR2 can operate in different experimental environments and applications FSSR2 is being evaluated in view of its possible operation for detector readout in a tracking system providing information to a first level trigger for both fixed target and collider experiments

16. Backup slides

17. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” Baseline restorer   Shaper output has small overshoot.   Overshoot causes unwanted variable offset at discriminator input.   BLR removes variable offset. Input signal discriminator scan without BLRInput signal discriminator scan with BLR

18. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” _ + Shaper output COMP VREF I 2I Threshold circuit input Baseline restorer

19. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” Threshold dispersion Peaking time [ns] Threshold dispersion [e rms] Low Gain High Gain Channels with BLR deselected 65 580460 85600470 125615485 Channels with BLR selected 65 440295 85440290 125490280

20. IEEE Nuclear Science Symposium, Puerto Rico, October 24 – 27, 2005 V. Re: “FSSR2, a Self-Triggered Low Noise Readout Chip for Silicon Strip Detectors” Output data format