A 40-m Range 90-frames/s CMOS Time-of-Flight Sensor Using SPAD and In-Pixel Time-Gated Pulse Counter

This letter presents a CMOS indirect time-of-flight (i-ToF) image sensor, which is based on a single-photon avalanche diode (SPAD) and a compact in-pixel time-gated pulse counter. The proposed SPADbased i-ToF sensor makes it possible to achieve a time-gated photon counting method at the pixel level and to enlarge a depth range up to 40 m while maintaining the pixel demodulation frequency up to 25 MHz. A prototype sensor is implemented in a 110-nm CMOS process and has a pixel array of 64 × 64 with a pixel pitch of 32 μm. With a 3-D frame rate of 90 frames/s, the sensor achieves high 3-D image quality with a nonlinearity error below 2.25% and a relative precision error of 0.51% at a maximum distance of 40 m.