A 25-Mpts/s Back-Illuminated Stacked SPAD Direct Time-of-Flight Depth Sensor With Equivalent Time Sampling and Pixel-Level Threshold Control for Automotive LiDAR

This article presents technologies for single-photon avalanche diode direct time-of-flight depth sensor and light detection and ranging (LiDAR) systems. The sensor includes a pixel readout circuit and comparators with threshold control, which achieve stable deadtime characteristics independent of process, temperature, and power supply voltage variations. It also enhances the LiDAR system performance under diverse background lighting conditions. Additionally, 3-GHz equivalent time sampling improves depth accuracy while maintaining a manageable data size. Extracting depth information from histograms reduces the data volume by approximately 98%, and pipelined parallel processing of sampling, signal processing, and sensor output improves the overall processing speed. The sensor delivers depth data at 20 frames/s with a horizontal and vertical angular resolution of 0.05°, covering a 120° horizontal and 26° vertical field of view, resulting in 25-Mpts/s depth data and object detection up to 300 m.