MOS-based active pixel sensor cell that utilizes the parasitic bipolar action of the cell to output image data

摘要

A MOS-based active pixel sensor cell utilizes the parasitic bipolar action of the cell to produce a horizontal current in lieu of the vertical image current associated with conventional bipolar-based active pixel sensor cells. Image data is collected during an integration period by applying a negative voltage to the gate of the MOS transistor which is sufficient to reverse-bias both the source/body and drain/body junctions. Following this, the image data is read out by raising the gate voltage such that the source/body junction remains reverse-biased, and the drain/body junction becomes forward-biased. Under these bias conditions, an amplified horizontal image current flows from the source, through the body, and out of the drain.