A Low-Power Mixed-Signal ASIC for SiPM Readout at Low Temperature

A mixed-signal ASIC developed to readout silicon photomultipliers (SiPM) at low temperature is presented. The chip is designed in a 110 nm CMOS technology. Both single photon counting and Time-over-Threshold (ToT) operating modes are supported. The ToT modality is useful when many photons pile-up to yield a continuous signal. In single photon counting mode an event rate of up to 5 MHz per channel can be accommodated. The time resolution is 50 ps and the target power consumption is less tha 5 mW per channel. The architecture of a first 32-channel prototype is described. Dedicated test structures to qualify critical building blocks at cryogenic temperature have also been deployed and experimental results will be discussed.