Range-Finding SPAD Array With Smart Laser-Spot Tracking and TDC Sharing for Background Suppression

We present the design and experimental characterization of a CMOS sensor based on Single-Photon Avalanche Diodes for direct Time-Of-Flight single-point distance ranging, under high background illumination short-range applications. The sensing area has rectangular shape ( $40\,\,\mathbf {\mathrm {\times }}\,\,10$ SPADs) to deal with backscattered light spot displacement across detector, dependent target distance, due non-confocal optical setup. Since only few SPADs are illuminated by laser spot, we implemented smart laser-spot tracking within active area, so define specific Region-Of-Interest (ROI) hit signal photons sharing timing electronics, significantly improve Signal-to-Noise Ratio (SNR) TOF measurements reduce overall chip power consumption. electronics consists 80 Time-to-Digital Converter (TDC) shared among 400 self-reconfigurable routing, which dynamically connects ROI available TDCs. latter have 78 ps resolution 20 ns Full-Scale Range (FSR), i.e., up 2 m maximum range. An on-chip histogram builder block accumulates TDC conversions provide final histogram. achieve precision better than 2.3 mm at 1 80% reflectivity, 3 klux halogen lamp kHz measurement rate. rejects 10 light, still m.