The ETROC Project: Precision Timing ASIC Development for CMS MTD Endcap Timing Layer (ETL) upgrade*

The MIP Timing Detector (MTD) of the Compact Muon Solenoid (CMS) will provide precision timing measurements with time resolution down to 30 ps level for every charged particle up to a pseudo-rapidity of |η|=3. This upgrade will mitigate the impact of pile-up interactions expected under the High-Luminosity LHC (HL-LHC) running conditions. The endcap region of the MTD, named the Endcap Timing Layer (ETL), will be comprised of a two-disk system of MIP-sensitive silicon low-gain avalanche diodes (LGADs), covering the high-radiation pseudo-rapidity region 1.6 < |η| < 3.0. The LGADs will be read out with the Endcap Timing Readout Chip (ETROC), which is designed to handle a 16×16 pixel cell matrix, each pixel cell being 1.3×1.3 mm^2 to match the LGAD sensor pixel size. We present recent progress in the design of ETROC and prototype testing results.