A SPAD Flash LiDAR Sensor With Push-Pull Analog Counter Achieving a 0.12% Depth Precision at a 70 m Depth Range

This article presents a$64 {\times } 64$SPAD flash LiDAR sensor that achieves a depth precision of 0.12% across a 70 m depth range. The sensor is built on a time-gated single-photon counting (TGSPC) architecture that integrates a back-side illuminated (BSI) single-photon avalanche diode (SPAD), a pulse-shaping circuit, a push-pull analog pulse counter, and column-parallel single-slope (SS) analog-to-digital converters (ADCs). A push-pull analog counter has been integrated into the pixel to significantly enhance the sensor’s ability to prevent saturation under high background light (BGL) conditions. Fabricated using a 110 nm BSI CMOS image sensor process, the sensor features a compact pixel pitch of$32~{\mu }$m and a high fill factor of 33%. For 3-D depth sensing, it operates at 30 fps with a power consumption of 29.1 mW. It achieves a high photon detection probability (PDP) of 14.3% at 850 nm, enabling a depth precision of 8.4 cm at a depth range of 70 m, corresponding to the depth precision of 0.12%. These results are achieved through the use of a compact SPAD front-end circuit, a novel push-pull analog counter, and an optimized SPAD structure.