Method and circuit for performing correlated double sub-sampling (CDSS) of pixels in an active pixel sensor (APS) array

摘要

A method and circuit for performing Correlated Double Sub-Sampling (CDSS) of pixels in an active pixel sensor (APS) array. The method and the apparatus subsamples a plurality (L²) of pixels by: storing L² analog reset charges output from the L² pixels into a first set of (N²) storage capacitors, and combining the (L²) reset charges; storing L² analog image signal charges output from the L² pixels into a second set of (N²) storage capacitors, and combining the (L²) image charges; and then obtaining a differential voltage (VS-VR) by subtracting (in the analog-domain) the voltage (VR) represented by the combined (L²) reset charges from the voltage (VS) represented by the combined (L²) image signal charges. When L equals one, the circuit performs conventional Correlated Double Sampling CDS upon the one pixel.