CMOS fingerprint sensor with automatic local contrast adjustment and pixel-parallel encoding logic

A CMOS fingerprint sensor is presented with a self-biasing automatic local contrast adjustment technique for image binarization realized with a passive capacitive network. Pixel-parallel cellular logic is embedded into the sensor array and extracts the characteristic features of the fingerprint image without any additional area consumption. This single-chip sensing and encoding system is suited for low-power and low-cost applications.