WORKSHOP PAPER
Threshold Uniformity Improvement in 1b QIS Readout Circuit
Abstract
A new readout architecture for single-bit Quanta Image Sensor (QIS) consisting of an amplifier before a 1-bit quantizer to improve the threshold uniformity of the readout cluster is proposed in this paper. A 2048x1024 high-speed test chip was implemented with 45nm/65nm stacked backside illuminated (BSI) CMOS image sensor (CIS) process and tested. The measured D-log-H results demonstrate good threshold uniformity in the range of 0.3 to 0.8 e- for all readout clusters at 500 frame per second (fps) equivalent timing with 68 mW power consumption. A coarse photon counting histogram (PCH) is obtained by sweeping quantizer threshold, showing 0.35e- r.m.s. read noise (including jot and readout circuit noise).Keywords
Quanta Image Sensor, Threshold Uniformity, Readout Circuitry,References
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