A 20×20-Pixels Mixed-Signal Silicon Photomultiplier with On-Chip Adjustable Front-End for Background Light Rejection

This paper presents a mixed-signal Silicon Photomultiplier (msSiPM) front-end for background light rejection. Each Silicon Photon Avalanche Diode (SPAD) output signal is digitized into a signal pulse with possibility of tuning fall time, in order to maximize the laser signal compared to background light. Then, all analog current signals are collected by a transimpedance amplifier (TIA) which provides an output voltage proportional to the number of triggered SPAD. As the architecture is mostly digital, msSiPM consumes a low static power consumption, equal to 428 μW. The receiver is composed by a 20×20-pixel array, and it is fabricated in a 0.11 μm CMOS technology reaching a pixel fill factor (FF) equal to 32.8%. Measurements have been carried out under different background photon fluxes, one stronger and one weaker, corresponding to 2.15 and 4.15 GPhotons/s at the SiPM, demonstrating strong background rejection in both conditions.