A Low Noise CMOS image sensor with pixel optimization and noise robust column-parallel readout circuits for low-light levels

Abstract

A low noise high sensitivity CMOS image sensor (CIS) is developed for low-light levels. The prototype sensor contains the optimized 1-Mpixel with the noise robust column-parallel readout circuits. The measured maximum quantum efficiency is approximately 60% at 660nm, and the long-wavelength sensitivity is also enhanced by a large sensing area and an optimized process. In addition, a low dark current of 0.96pA/cm2 at 292 K, a low temporal random noise in a readout circuitry of 1.17erms, and a high pixel conversion gain of 124 ìV/e- are achieved. The implemented CMOS imager using 0.11 ìm CIS technology with a pinned photodiode has a very high sensitivity of 87V/lx•sec that is suitable for the scientific applications such as medical imaging, bioimaging, surveillance cameras, and so on.