A Low Noise Read-Out IC with Gate Driver for Full Front Display Area Optical Fingerprint Sensors

It is presented the first read-out IC (ROIC) for a TFT-based full-screen optical fingerprint (FP) sensor placed under the OLED display. The ROIC supports both the fast-scan mode to acquire 256×256 pixels FP image in anywhere on the display, and the full-scan mode to acquire a full-screen FP image (2,560×1,280 pixels). 2nd order correlated double sampling (CDS) and noise compensation techniques are used for low noise and leakage immunity. A low-cost single-slope ADC (SS-ADC) with enhanced input dynamic range (DR) per channel enables fast FP scans and a large area sensing without excessive die area increase. A breakdown voltage (BV) protection circuit allows the gate driver and IO pad in the ROIC to be driven up to 18V pp (±9V) using 9V devices. The IC was fabricated in a 90nm CMOS process. Sensing area, measured SNR, sensing time, and power consumption are 12.8×6.4cm2 with 508dpi, 17dB, 208ms, and 56mW at 2.8V, respectively.