A Sensitivity and Linearity Improvement of a 100-dB Dynamic Range CMOS Image Sensor Using a Lateral Overflow

Abstract

In a CMOS image sensor featuring a lateral overflow integration capacitor in a pixel, which integrates the overflowed charges from a fully depleted photodiode during the same expo- sure, the sensitivity in nonsaturated signal and the linearity in sat- urated overflow signal have been improved by introducing a new pixel circuit and its operation. The floating diffusion capacitance of the CMOS image sensor is as small as that of a four transistors type CMOS image sensor because the lateral overflow integration capacitor is located next to the reset switch. A 1/3-inch VGA format /40/54/52/48/72 /52/56/48/86pixels/41, /55 /53 /55 /53 m/50pixel color CMOS image sensor fabricated through 0.35- m two-poly three-metal CMOS process results in a 100 dB dynamic range characteristic, with im- proved sensitivity and linearity.