Silicon Strip Readout and the XYTER Electronics Development Christian J. Schmidt et al., GSI Darmstadt 10th CBM Collaboration Meeting, Dresden, Sept. 24. – 28., 2007

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Challenging Experiments, Challenging Detector Specs As a fixed target machine, very high event-rates (1000 tracks at 10MHz for CBM) Up to 5% channel occupancy, Very inhomogeneous track distribution (forward cone)  Signal latency will be too large for a timely, reasonable trigger decision,  Event overlap expected Need front-end electronics: MIPs at high input capacitance highly integrated, asynchronous, autonomous hit detection, time stamp labeling.

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Additionally Very harsh radiation environment (10 MRad) Very high density channels with need for either  low radiation-length detector design (CBM-STS, PANDA TPC, PANDA forward GEM trackers, CBM TRD)... or  very compact detector design (e.g. CBM-Muon Chambers)

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 n-XYTER: Novel FE-Chip Architecture Cast in Silicon Architectural Solution for FAIR CBM and PANDA. Starting point towards a FAIR dedicated XYTER front-end ASIC Our work-horse readout ASIC for detector prototyping detector readout ASIC for high-density and high statistical rate time and amplitude measurement µ pitch freely running, self triggered autonomous hit detection 850 (1000) ENC at 30 pF dynamic range for 6 MIPs (300µ Si) positive and negative signals Per channel analogue energy and digital time stamp FIFO (1ns resolution) De-randomizing, sparsifying Token Ring readout at 32 MHz n-XYTER was developed for neutron applications within EU FP-6 NMI3

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 charge preamp FAST shaper 18.5 ns peaking SLOW shaper (2 stages) 140 ns peaking time Peak detector & hold, free running comparator Time Walk Compensation circuit PDH reset pulse height output trigger timestamp reg. charge input Data Driven Front-End: Asynchronous Channel Trigger dig. FIFO analogue FIFO Asynchronous registry and storage in 4-level fifo guarantees data loss < 4 % when read-out through token ring The DETNI ASIC 1.0, a front-end evaluation chip in AMS 0.35µ detection of statistical, poisson distributed signals

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Analogue Signal Sequence (Test Channel) Testpulse Release Slow Shaper Fast Shaper Discriminator Output

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Test Board for Tests on n-XYTER  64/128 chan. connected  I²C-Interface  Test points accessible  All functional tests possible  Digital output accessible One additional analogue test channel is available for direct access of slow and fast shaper outputs... with output buffer would have been even more useful

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Analogue Pulses, Peaking Time, Front-End Noise FAST channelSLOW channel ENC26.9 e/pF e12.7 e/pF e peaking time a (1% to 99%) 18.5 ns139 ns Engineered for 30 pF, giving (850 ) 1000 e 600 e pre-amp and shaper power consumption: 12.8 mW per channel; OK for neutrons!

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Slow Shaper Output, the Energy Channel Measurements on the test channel #129 varying input charge varying input capacitance

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Some Inter-Channel Pick-Up, Ongoing Detective Work C in = 0 pF, bond wire removed System Effect No dependence upon no. of bond wires, power or gnd May be worsened with discriminator settings (TWC) C in = 22 pF Feedback via spurious coupling through epitaxial, optical layer, substrate to the input

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Some In-Channel Discriminator Feedback Detected...upon removal of discriminator-power decoupling These issues are particularly important with the self triggered architecture! They will be addressed even more in the next engineering run. correlates with internal discriminator trigger correlates with external test-pulse release signal (blue)

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Channel layout overview, Clock Domains and Power analogue front end, PDH comp – TWC trim reg mask reg. analogue mem. ch. ID token cell TS latch digital mem. mono synch control input MOS GND analogue GND & BULK analogue VDD A/D guard ring digital BULK digital GND digital VDD clock tree comparator VDD memory control ( 9 bit ) PDH reset comp PAD analogue domain no clock digital domain system clock 8 mm time stamp fast clock 5 mm total of 4 nF on chip MIM caps

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Token Ring Readout, Data Transmission Data Valid TS grey coded Ch# grey coded data transfer tested at 35 MHz, will also work at 128 MHz Measurement: Transmission of four data elements on channels 1, 8, 30, 82

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Analogue Differential Output, the Energy Channel Signal settling upon successive data Three signals, one signal altered

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Power Consumption preamplifier 7.4mW fast shaper 2.5mW slow shaper stage mW slow shaper stage mW discriminator 2.1 mW peak detector and hold 2.7 mW analogue FIFO 2.3 mW overall we find 21 mW/channel operating power

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Testing Summary Slow Control Operative Clocking at 256 MHz possible Grey coded time stamp generated Analogue readout operative Features operative: Positive and negative signal processing Global threshold, local threshold fine tune On chip test pulse generation Channel masking Channel forced trigger (baseline determination) Individual channel shut down Pile-up lableing, fifo overflow identification Testers involved: Gerd Modzel (PI HD) Markus Höhl (GSI) Knut Solvag (GSI) Sharma Anurag (Dehli) Rafal Lalik (AGH, GSI) Adam Czermak (AGH) thanks for his support to Sven Loechner (GSI) and others

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 n-XYTER Engineering Run in Preparation Engineering Run Targeted for Jan H. K. Soltveit (PI Heidelberg) Addresses active feedback baseline adjustment  full dynamic range, no temp. co. on base-line Addresses spurious feedback coupling through substrate Reduction of power consumption where easily possible From 250 Dies to Work Horse Electronics for Detector Prototyping Will yield several thousand chips for prototyping of CBM STS, PANDA TPC and other detectors as well as the DAQ chain and beyond. Go Detector Prototyping

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Dedicated XYTER Development for FAIR Generic n-XYTER architecture finds broad applications within FAIR: CBM Silicon Strips STS, High Rate GEM TPC as well as large area gas detectors (micro structures or wire chambers) Twin chip development with XYTER architecture and diversities for: Radiation hard design in UMC 0,180 µm (better than 10 MRad) Minimized power consumption Integration of modern, low power ADC on chip  purely digital interface Highly multiplexed data interface (minimize cableing) Optimized system synchronization capabilities SEU tolerance Detector DC coupling capability Dense mounting capability Silicon Strip MIP detection, micro-structured gas detectors Larger dynamic range, ion tail cancellation specialties

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Groups Involved In XYTER Development AGH Krakow, (Robert Szczygiel, Pawel Grybos et al.) TI Heidelberg (Peter Fischer and Tim Armbruster) MEPHI, Moscow (E. Atkin et al) PI Heidelberg and HD ASIC-Lab (H. K. Soltveit) GSI Darmstadt, C.J. Schmidt (coordination) and Sven Loechner Further engaged: S. Chattopadhyay et al, Kolkatta on individual design items University Bergen, K. Ulaland and D. Röhrig et al We will structure the XYTER development collaboration Friday morning 9:00 to 11:00 CBM

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Thank you for your attention CBM

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Token Ring Architectural Pros/Cons High Efficiency Empty channels automatically skipped in readout process Built-in fair distribution of readout bandwidth, automatic bandwidth focussing Built-in De-Randomization: 100% bandwidth used on data Error Robustness Any problematic channel (e.g. continuously firering) will divert and occupy a maximum of 1/n th of the bandwidth. Built-in, non-perfect readout probability avoids unrecoverable logic deadlock: Problematic situations like any kind of pile-up, logic hang-ups or glitch cause mere deadtime but the “show will go on”. But: Data needs to be tagged with a time-stamp Data needs to be resorted and re-bunched after readout

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Investigating Individual Channels, Triggerefficiency Trigger efficiency in Treshold Scan: The S-Curves - Input of test pulses at fixed rate, - scan threshold while measuring detection rate Derivative gives image of noise!

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Trigger efficiency tested for all channels origin of 2 ch periodicity attributed to four fold pulser circuitry Channel number note bonded and non-bonded channels

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Token Ring Readout Process  Focus bandwidth where there is data  32 MHz data readout  Automatic zero suppression (sparsification) Analog FIFO Timestamp FIFO data readout bus token cycle Disc. token cell control logic for data readout or token pass skip channels without data, asynchronously rush through empty channels until data found

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 Modelling FIFO Occupancy FIFO can virtually be filled with up to 2*n events with no data loss since n elements are read while data comes in. Poisson Distribution( ): e.g.: fifo depth n = 4, so expect 4 events during readout if incoming rate equals maximum readout rate.  = 4.

10th CBM Collaboration Meeting, Dresden Sept. 24 – 28, 2007 n-XYTER Front-End Topology