A 32×32 SPAD Array Based Readout Integrated Circuit for LiDAR Applications

This paper presents a readout integrated circuit (ROIC) for 32×32 single photon avalanche diode (SPAD) array. The ROIC integrates 32×32 active quenching circuit and time-to-digital converter (TDC) circuit. Each ROIC unit has a novel active quenching circuit (AQC) and an in-pixel TDC. The ROIC and the detectors are integrated by Flip-Chip .The novel quenching circuit with active reset function is proposed to reduce the dead time. A dual-counter-based TDC is designed to prevent the metastability of the counter. The sensor is fabricated in 180-nm CMOS BCD technology. The simulation results show the novel active quenching circuit effectively reduces the dead time down to 10 ns. The 13bit-TDC helps the system achieve centimeter-accuracy detection.