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 $428 \mu \mathrm{~W}$. The receiver is composed by a $20 \times \mathbf{2 0}$-pixel array, and it is fabricated in a $0.11 \mu \mathrm{~m}$ 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.