7.2 A 48×40 13.5mm Depth Resolution Flash LiDAR Sensor with In-Pixel Zoom Histogramming Time-to-Digital Converter
Bumjun Kim, Seonghyeok Park, Jung‐Hoon Chun, Jaehyuk Choi, Seong‐Jin Kim
Abstract
3D imaging technologies have become prevalent for diverse applications such as user identification, interactive user interfaces with AR/VR devices, and self-driving cars. Direct time-of-flight (D-ToF) systems, LiDAR sensors, are desirable for long-distance measurements in outdoor environments because they offer high sensitivity to weak reflected light and high immunity to background light thanks to the spatiotemporal correlation of SPADs [1], [2]. SPAD-based LiDAR sensors suffer from a large amount of ToF data generated by complicated time-to-digital converters (TDC), resulting in limited spatial resolution and frame rate compared with indirect ToF (I-ToF) sensors. Recently, LiDAR sensors embedding histogramming TDCs have been reported to generate depth information to reduce the required output bandwidth [3]-[6]. However, they still adopt a large number of memories in pixel, a complicated signal processor, or a column-parallel TDC scheme with scanning optics.