High dynamic range cmos image sensor pixel with reverse biased metal-insulator-metal lateral overflow integration capacitor for reduced image lag

Abstract

A pixel circuit includes a transfer transistor is coupled between a photodiode and a floating diffusion to transfer the image charge from the photodiode to the floating diffusion. A lateral overflow integration capacitor (LOFIC) includes an insulating region between a first metal electrode and a second metal electrode that is coupled to a first reset transistor and selectively coupled to the floating diffusion. A second reset transistor and a bias voltage source are coupled to the first metal electrode. During an idle period, the first reset transistor is configured to be on, the second reset transistor is configured to be off, and the bias voltage source is configured to provide a first bias voltage to the first metal electrode to reverse bias the LOFIC. The first bias voltage is less than a reset voltage provided from the reset voltage source.