An Ultra-Low Power PPG and mm-Resolution ToF PPD-Based CMOS Chip Towards All-in-One Photonic Sensors

This paper presents a CMOS photonic sensor covering multiple applications from ambient light sensing to time resolved photonic sensing. The sensor is made of an array of gated pinned photodiodes (PPDs) averaged using binning and passive switched-capacitor (SC) charge sharing combined with ultra-low-power amplification and analog-to-digital conversion. The chip is implemented in a 180 nm CMOS image sensor (CIS) process and features high sensitivity, low-noise and low-power performance. Measurement results demonstrate $\mu \text{W}$ health monitoring through Photoplethysmography (PPG), 10 ps resolution for time resolved light sensing and mm precision for time-of-flight (ToF) distance ranging obtained with a frame rate of 50 Hz and 20 dB ambient light rejection.