An image sensor with in-pixel selective-charge-subtraction circuits for selective light detection

Abstract

In this paper, a CMOS Image Sensor (CIS) capable for in-pixel selective light detection and background light suppression is presented. The pixel circuit is composed of demodulation transistors and Adaptive Charge Unit (ACU), realizes in-pixel selective-charge-subtraction. Demodulation transistors are used for selective light detection. And ACU is used for background light subtraction to prevent saturation for wide dynamic range. The presented image sensor has been fabricated in 0.18-µm CMOS process and successfully tested, and it has a 64 × 64 pixel array. The minimum signal-to-background ratio (SBR) is −18.8 dB and the dynamic range is 89.3 dB.