A 2.6 μW Monolithic CMOS Photoplethysmographic (PPG) Sensor Operating With 2 μW LED Power for Continuous Health...

Photoplethysmography (PPG) enables wearable vitals monitoring. Nevertheless, it is still limited by the few mA of the LEDs driving current. We present a PPG sensor integrating an array of dedicated pinned-photodiodes (PPD) with a full readout chain integrated in a 0.18 μm CMOS Image Sensor (CIS) process. The sensor features a total input referred noise of 0.68 e-rms per PPD, independently of the input light, and achieves a 4.6 μW total power consumption, including the 2 μW LED power, at 1.38 bpm heart rate average error.