A 785nW Multimodal (V/I/R) Sensor Interface IC for Ozone Pollutant Sensing and Correlated Cardiovascular Disease Monitoring

This paper presents a 785nW multimodal sensor interface IC enabling ozone pollutant sensing and correlated cardiovascular disease (CVD) monitoring based on electrocardiography (ECG) and photoplethysmography (PPG). The interface IC consists of a 165nW voltage-mode ECG channel, a 532nW current-mode PPG channel, a 75.6nW resistive ozone channel, and 12.6nW peripheral circuits, all at 0.6V. A 4MΩ-gain regulated cascode transimpedance amplifier (RGC-TIA) with a hybrid DC offset current cancellation (DCOC) loop reduces the PPG readout power by 37×, compared to state-of-the-art PPG sensor interfaces. Fabricated in 65nm CMOS, the proposed IC is tested with a custom digital readout IC. The full system power consumption with an LED is 11.5μW, which is 54× less than prior ozone/CVD joint-monitoring sensor interface systems.