A 0.18µm CMOS SoC for a 100m-range 10fps 200×96-pixel time-of-flight depth sensor

Abstract

A number of potentially low-cost time-of-flight (ToF) 3D image sensors aiming at consumer electronics applications have recently appeared in CMOS. Diffused-light sensors taking advantage of SPAD pixels, conventional and pinned-photodiode lock-in pixels demonstrate centimeter-ranging performance in distances of typically up to 6m, and with the exception of, under low background light (BG) conditions. In those approaches, however, performance tends to rapidly deteriorate in severe BG conditions, such as outdoors, and long-distance ranges have yet to be reported. Another common limitation is their inability to cope with multi-echo target environments. Higher optical signal-to-background ratio (SBR), and hence better performance, is typically achieved by laser-scanning approaches, e.g. employing polygonal or MEMS mirrors. With the emerging need for high-resolution light detection and ranging (LIDAR) technologies in advanced driving-assistance systems (ADAS), we introduce an SoC that performs time-correlated single-photon counting (TCSPC) and complete DSP for a 100m-range ToF sensor. The chip provides the system-level electronics with a serial and low-bit-rate digital interface for: multi-echo distance, distance reliability, intensity, and BG-only intensity, thus mitigating system-level complexity and cost.