A 368 × 184 Optical Under-Display Fingerprint Sensor With Global Shutter and High-Dynamic-Range Operation

Abstract

This study proposes a 368 $\times 184$ optical under-display fingerprint sensor designed and prototyped using $0.11-\mu \mathrm{m}$ CIS technology. The prototype sensor with global shutter operation and an ADC-embedded in an 8-pixel configuration features low noise, low-power consumption, fast response time, and a smaller signal processing circuit area. Two sets of memory (184 × 92 bytes) are also embedded in the pixel array to save external memory cost. A dynamic range of 126 dB is achieved with 8-segment auto exposure and dark level adjustment with programmable gain control. The prototype fingerprint sensor was successfully embedded in a mobile phone for functional verification, and the power consumption was only 25 mW with a 3.3 V supply voltage. The sensor has a chip size of 9.74 mm $\times 4.6$ mm, a resolution of 1154 dpi, and a sensing area of 73%.