A WDR CMOS Image Sensor Employing In-pixel Capacitive Variation using a Re-configurable Source Follower for Low Light Applications

摘要

A wide dynamic range image sensor that uses a 5-transistor pixel architecture to provide user-programmable conversion gain enhancement for detection of low illumination signals is presented. The dynamic range enhancement is a result of periodic variation of the gate-bulk capacitance of the in-pixel source follower by re-configuring it as a MOS capacitor. The pixel is capable of providing standard integrated photo-signal in high illumination and amplified signal in low illumination. A prototype sensor containing a 64 × 64 array of the proposed pixels has been fabricated in AMS 0.35 μm, 3.3 V CMOS technology to verify the operation. The 10 × 10 pixel has a 20.25% fill factor. The in-pixel signal amplification results in a dynamic range enhancement of 18 dB under low illumination condition and a conversion gain enhancement of 160 μV/e