Ximenes, Augusto RonchiniPadmanabhan, PreethiLee, Myung-JaeYamashita, YuichiroYaung, Dun-NianCharbon, Edoardo2019-11-152019-11-152019-11-152019-11-0110.1109/JSSC.2019.2938412https://infoscience.epfl.ch/handle/20.500.14299/163132WOS:000493176300024This article introduces a modular, direct time-of-flight (TOF) depth sensor. Each module is digitally synthesized and features a 2 $\times $ (8 $\times $ 8) single-photon avalanche diode (SPAD) pixel array, an edge-sensitive decision tree, a shared time-to-digital converter (TDC), 21-bit per-pixel memory, and in-locus data processing. Each module operates autonomously, by internal data acquisition, management, and storage, being periodically read out by an external access. The prototype was fabricated in a TSMC 3-D-stacked 45/65-nm CMOS technology, featuring backside illumination (BSI) SPAD detectors on the top tier, and readout circuit on the bottom tier. The sensor was characterized by single-point measurements, in two different modes of resolution and range. In low-resolution mode, a maximum of 300-m and 80-cm accuracy was recorded; on the other hand, in high-resolution mode, the maximum range and accuracy were 150 m and 7 cm, respectively. The module was also used in a flexible scanning light detection and ranging (LiDAR) system, where a 256 $\times $ 256 depth map, with millimeter precision, was obtained. A laser signature based on pulse-position modulation (PPM) is also proposed, achieving a maximum of 28-dB interference reduction.Engineering, Electrical & ElectronicEngineeringdecision treeslaser radardelayscmos technologydistance measurementinterferencedepth sensorinterference reductionlaser signaturelight detection and ranging (lidar)ranging imagingsingle-photon avalanche diode (spad)3-d-stackingtime-of-flight (tof) imagingcameratext::journal::journal article::research article