A 38µm Range Precision Time-of-Flight CMOS Range Line Imager with Gating Driver Jitter Reduction Using Charge-Injection Pseudo Photocurrent Reference

Abstract

Contactless 3D scanning systems have attracted rising attention in many fields like industrial measurements, medical systems, and even consumer products. Recently, the range precision of time-of-flight (ToF) CMOS image sensors have been gradually improved using high-speed lock-in pixels [1]–[3], and the possibilities of ToF image sensors in their application to small-size cost-effective 3D scanning systems with sub-1 00µm precision were previously presented [4]. However, the range precision is influenced by jitter owing to gate drivers, causing a large column-to-column variation of precision. The driver jitter includes a 1/f noise component, so the range precision cannot be reduced even using frame averaging. A frequency-modulated continuous-wave (FMCW) LiDAR that has sub-10µm precision is another candidate for high-precision 3D scanners [5]. However, the FMCW LiDARs only have a single or a few receiver channels. Thus, high-speed 2D mechanical scanning is required for a 3D scanning system. In addition, the FMCW LiDAR using optical coherence in the range measurements has difficulties in real applications, such as a limitation in materials to be measured, system, and large required optical power.