A 256 × 192 -Pixel Direct Time-of-Flight LiDAR Receiver With a Current-Integrating-Based AFE Supporting 240-m-Range Imaging

This article presents a direct time-of-flight (DToF) LiDAR with a current-integrating-based analog frontend (AFE), performing long-range (LR) and high-quality imaging. A current-integrating-based transimpedance amplifier (CI-TIA) facilitates a direct current-to-pulse conversion, which not only achieves superior transimpedance gain and noise performance but also adaptively compensates the background-light-induced direct current to alleviate the dynamic range (DR) obstacle in the LR LiDARs. Benefiting from the pulse manner output of the CI-TIA, a pulse position and width converter (PPWC) utilizes lightweight counters to provide the time and intensity information simultaneously, while the latter compensates for the walk error in time intrinsically. Furthermore, the intensity is used to adapt the accumulation window size to improve the imaging quality under high intensity. The prototype LiDAR receiver is fabricated in a 65-nm CMOS process, which achieves a consistent distance error of <1 cm and precision of <0.09% for up to 240-m measurements. It demonstrates a $256{\times } 192$ -pixel resolution imaging at 30 frames per second (fps) with the assistance of a scanning system.