CMOS ACTIVE PIXEL IMAGE SENSORS FOR HIGHLY INTEGRATED IMAGING-SYSTEMS

A family of CMOS-based active pixel image sensors (APS's) that are inh erently compatible with the integration of on-chip signal processing c ircuitry is reported, The image sensors were fabricated using commerci ally available 2-mu m CMOS processes and both p-well end n-well implem entations were explored, The arrays feature random access, 5-V operati on and transistor-transistor logic (TTL) compatible control signals. M ethods of on-chip suppression of fixed pattern noise to less than 0.1% saturation are demonstrated. The baseline design achieved a pixel siz e of 40 mu m x 40 mu m with 26% fill-factor. Array sizes of 28 x 28 el ements and 128 x 128 elements have been fabricated and characterized, Typical output conversion gain is 3.7 mu V/e(-) for the p-well devices and 6.5 mu V/e(-) for the n-well devices, Input referred read noise o f 28 e(-) rms corresponding to a dynamic range of 76 dB was achieved, Characterization of various photogate pixel designs and a photodiode d esign is reported, Photoresponse variations for different pixel design s are discussed.