Image sensor and pixel that has switchable capacitance at the floating node

摘要

A pixel and image sensor formed in accordance with the present invention has two modes of operation: a high illumination mode and a low illumination mode. The present invention switches on an auxiliary capacitance at the floating node based upon the amount of illumination on the image sensor. The amount of illumination on the image sensor can be determined in a variety of ways. Once the level of illumination is determined, a decision is made by comparing the level of illumination to a threshold whether to switch on the auxiliary capacitance (for high illumination) or not switch on the auxiliary capacitance (for low illumination).