An $80\times25$ Pixel CMOS Single-Photon Sensor With Flexible On-Chip Time Gating of 40 Subarrays for Solid-State 3-D Range Imaging

A CMOS solid-state 3-D range imager that uses short (~110 ps) laser pulses and a novel flexible time gating scheme for a single-photon avalanche diode (SPAD) array is presented. The array is divided into 40 subarrays for which a narrow (<;0.8 ns) time gating position can be set and scanned independently. The imager can be set to measure multiple regions of interest by means of the flexible time gating of the subarrays. The time gating for each of the subarrays is selected separately with an on-chip delay-locked loop (DLL) block that has 240 outputs and a delay grid of ~100 ps. The prototype has 80 × 25 pixels overall with 10 × 5 pixel subarrays. The fill factor of the sensor area is 32%. A 3-D range image is demonstrated at ~10 frames/s with centimeter-level precision in the case of passive targets within a range of ~4 m and a field of view of 18° × 28°, requiring an average active illumination power of only 0.1 mW.