A CMOS integrated capacitive fingerprint sensor with 32-bit RISC microcontroller

The SOC implementation of a capacitive fingerprint sensor, which embeds the 32-bit microcontroller for performing an identification algorithm, is described for user authentication on small, thin, and portable equipment. The SOC is composed of a 160×192 pixel array with a sensor detection circuit and the embedded 32-bit RISC microcontroller. The proposed sensor detection circuit increases the voltage difference between a ridge and valley about 180% more than conventional detection circuit does and minimizes any electrostatic discharge influence by applying an effective isolation structure. The test chip was fabricated on a 0.35-μm standard CMOS 1-poly 4-metal process.