Memoryless Wide-Dynamic-Range CMOS Image Sensor Using Nonfully Depleted PPD-Storage Dual Capture

Abstract

A new low-cost high-performance dual-capture image sensor for wide-dynamic-range (WDR) applications is proposed. The proposed pixel uses a pinned photodiode (PPD) as a charge storage to achieve a WDR operation capability. By controlling the applied voltage at a transfer gate (TG) of the pixel to operate the PPD in a nonfull-depletion operation mode, the fixed pattern noise (FPN) that originated from the threshold characteristic variation of the TG is efficiently calibrated without additional circuitry or image processing steps. The prototype sensor was fabricated by using a 0.13-mu m CMOS image sensor process. The chip includes a 320 x 240 pixel array with a 2.25-mu m pixel pitch. A WDR of 91 dB has been achieved from the proposed operation mode while maintaining an FPN less than 0.7% over the entire dynamic range.