Active pixel sensor with photo diode discharge

摘要

A pixel cell (30,40) and an active pixel sensor (20) that incorporates that pixel cell. Various embodiments of discharge circuitry (36,44) are disclosed and these embodiments achieve a discharging of the photo diode (31,41) of each pixel cell. In one embodiment, a discharge transistor (36) in coupled to the output node of the photo diode to achieve selectable discharge. In another embodiment, the voltage supply to the photo diode may be switchable coupled between a high level and a low level reference voltage. <IMAGE> <IMAGE>