A high sensitivity capacitive fingerprint sensor with double sensing plates

This paper introduces a single-chip capacitive fingerprint sensor implemented in a standard CMOS technology. The fingerprint pattern is captured by detecting the different values of the capacitors composed of the skin surface and the electrode in the device. The sensor is comprised of an array of sensing cells. Each cell contains a high sensitive readout circuit and a sensing device, which has double metal plates to detect the small capacitance.