A Dual-Capture Wide Dynamic Range CMOS Image Sensor Using Floating-Diffusion Capacitor

A dual-capture wide dynamic range CMOS image sensor using an in-pixel floating-diffusion (FD) storage capacitor is proposed. The proposed structure uses the FD as a storage capacitor. The potential of the FD node is read out using a floating-gate capacitor without a contact metallization of the FD node to reduce the leakage. The proposed sensor was fabricated using a 0.35-mum CMOS process. The chip includes 320 times 240 pixels whose pitch is 5.6 mum and whose fill factor is 36%. The measurement results show 100-dB dynamic range, and the leakage at the non-metalized FD is reduced to about one-third of that of the conventional FD with the contact metallization.