The ETROC Project: Precision Timing ASIC Development for LGAD-based CMS Endcap Timing Layer (ETL) Upgrade

Abstract

The ETROC (Endcap Timing Readout Chip) is being developed for the LGAD-based CMS Endcap Timing Layer (ETL) at HL-LHC. The ETL on each side of the interaction region will be instrumented with a two-disk system of MIP-sensitive LGAD silicon devices to be read out by ETROCs for precision timing measurement with down to 30 ps timing resolution. The ETROC is designed to handle a 16 x 16 pixel cell matrix, with each pixel cell being 1.3 mm x 1.3 mm to match the LGAD sensor pixel size. Approximately 15% of the sensors near the highest eta region will experience hadron fluence above 1e15 neq/cm 2 towards end of operation of HL-LHC, resulting in small signal amplitude with LGAD gain reduced to around 10. For this reason, the front-end design for preamplifier and discriminator has been specifically optimized for the reduced LGAD signals, with enough flexibilities to meet the ETL specific needs for time resolution, power budget and radiation profile.

4D Tracking: Present Status and Perspective

“…Both collaborations are developing new read-out ASICs for their respective timing layers: ALTIROC [30] designed in 130 nm CMOS technology by ATLAS and ETROC [31] in 65 nm CMS technology by CMS. ALTIROC and ETROC are the first attempts to develop large ASICs (about 2x2 cm 2 ) dedicated to reading LGAD sensors, aiming at a sensor-electronics combined single hit resolution below 50 ps.…”

Fast (optical) Links

“…The past-decade has seen tremendous advances in particle detector developments, exemplified in pixel sensors [1], high-granularity calorimeters [2] and time (of arrival) detectors [3,4] for MIPs in a jet. R&D efforts are also seen in dedicated sensor readout ASICs [5,6], ondetector readout electronics and data transmission to off-detector processing units [7]. In data transmission we have progressed from tens of mega-bits per second (Mbps) per channel to the present 10 Gbps per channel, and migrated from mainly coaxial-cable based transmission medium to optical fibers.…”