A locally autocompensating image sensor

A locally autocompensating image sensor was designed and fabricated in a 0.35 μm standard CMOS process. Every pixel contains an automatic compensation circuit made of 13 transistors and 4 capacitors on an area of 38×38 μm² that compensates the part of the photocurrent caused by undesired background illumination. This allows the capture of extremely weak optical signals in scenes with background illumination several hundred times stronger than the active signal. A prototype pixel array with fixed pattern noise (FPN) correction is presented, which demonstrates the enhanced performance of the sensor concept.