A 25M Points/s Back-Illuminated Stacked SPAD Direct Time-of-Flight Depth Sensor with Equivalent Time Sampling for Automotive LiDAR
Tatsuya Yui, Katsuhiko Hanzawa, Masahiro Hosoya, Yuqing Liu, Tadashi Yasufuku, Yoshinori Tanaka, Yoshiaki Tashiro, Albert Tumewu, Masataka Yamane, Masatoshi Shibata, Toshiki Sakada, K. Akatsuka, Yudai Matsushita, K. Yamada, Kouji Mori, Takahiro Toyoshima, Yorito Sakano, Oichi Kumagai, Kenichi Tsunoji, Masayuki Takahashi
Abstract
This paper presents technologies at Single Photon Avalanche Diode (SPAD) direct Time-of-flight (ToF) depth sensor and Light Detection and Ranging (LiDAR). Method of readout by under-pixel differential comparator and the threshold control can select either to prioritize distance accuracy or acquisition of reflectance information. The equivalent time sampling (ETS) at 3 GHz improves depth accuracy. Furthermore, subsequent 250MHz re-sampling and the depth information extraction pipeline relaxes the operation frequency maintaining the depth accuracy and approximately 98% data size reduction. Sensor delivers distance measurement for 520 effective macro pixels with 0.05° vertical angular resolution at 120° horizontal Field of View (FoV) and 20fps, resulting in 25M points/s (pts/s) ranging data and detection of 25cm object at 250m.