Park, Byungchoul Park, Injun Park, Chanmin Choi, Woojun Na, Yoondeok Lee, Myung-Jae Chae, Youngcheol 2024-01-19T13:33:48Z 2024-01-19T13:33:48Z 2022-01-10 2021-10 0018-9200 https://pubs.kist.re.kr/handle/201004/116325 This article presents a 64 x 64 indirect time-of-flight (iToF) image sensor with a depth range of 50 m, integrated into a 1P4M 110-nm CMOS process. The sensor is based on a single-photon avalanche diode (SPAD), the range-dependent phase delay of which is measured by compact analog time-gated pulse counters and then read out by column-parallel single-slope (SS) analog-to-digital converters (ADCs). We present two prototypes of iToF sensors that exploit one- or two-tap counters in the pixel. Compared to the one-tap sensor, the two-tap sensor achieves an improved fill factor of 26.3% with a pixel pitch of 32 mu m. This improvement is realized by using a retrograde deep n-well as guard-ring structure and two analog counters whose layout has been optimized. By utilizing two different demodulation frequencies of 1.56 and 50 MHz, the two-tap sensor achieves a large depth range of 50 m with a relative depth uncertainty of 0.22% and a high 3-D frame rate of 65 frames/s. When using an optical bandpass filter and multi-frame accumulation, the sensor shows a tolerance of 120-klx sunlight. Compared with the previous iToF benchmarks, the proposed SPAD-based iToF sensor demonstrates the largest depth range without compromising the relative depth uncertainty. English IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC A 64 x 64 SPAD-Based Indirect Time-of-Flight Image Sensor With 2-Tap Analog Pulse Counters Article 10.1109/JSSC.2021.3094524 1 IEEE JOURNAL OF SOLID-STATE CIRCUITS, v.56, no.10, pp.2956 - 2967 IEEE JOURNAL OF SOLID-STATE CIRCUITS 56 10 2956 2967 scie scopus 000698895200012 2-s2.0-85110913165 Engineering, Electrical & Electronic Engineering Article 3-D imaging analog counter CMOS timeof-flight (ToF) sensor global shutter indirect ToF (iToF) sensor single-photon avalanche diode (SPAD) SPAD-based iToF sensor time-gated pulse counter