Patent ID: 7209173
Filing Date: 2007-04-24
Classification: H01L,H04N

Abstract:
1. A method of operating an imager device: performing a first reset operation on a plurality of pixels, wherein the first reset operation charges photo diodes of the plurality of pixels to an initial level substantially equal to a gate voltage of a corresponding transfer transistor coupling the photo diodes to floating diffusion regions; collecting photoelectrons with the photo diodes, wherein a portion of the photoelectrons exceeding the initial level is coupled through the transfer transistor to a corresponding floating diffusion region of the plurality of pixels; sampling a first voltage level of the floating diffusion region to determine a photosignal; performing a second reset operation on the plurality of pixels, wherein the second reset operation charges the photo diodes to the initial level; and following the second reset operation, sampling a second voltage level of the floating diffusion region to determine a reset level, wherein a voltage difference between a signal level of the photosignal and the reset level represents the photoelectrons collected by the photo diode.