부산대학교 도서관

In this article, we present the design and analysis of a 785-nW multimodal sensor interface IC for ozone pollutant sensing and correlated cardiovascular disease monitoring based on electrocardiography (ECG) and photoplethysmography (PPG). The proposed hybrid $dc$ offset current cancellation (DCOC) along with a 4- $\text{M}\Omega $ gain-regulated cascode transimpedance amplifier (RGC-TIA) enable PPG readout power reduction by $37\times $ , compared with the state-of-the-art PPG sensor interfaces. The ozone sensing channel proposes an adaptive architecture to enable low $V_{\text {DD}}$ operation, achieving a $300\times $ power reduction, compared with the state-of-the-art gas sensing readouts. The ozone sensing channel’s performance was also verified using custom resistive metal-oxide sensors for concentrations from 50 to 900 ppb. The sensor interface IC is fabricated in a 65-nm CMOS, integrating a 165-nW voltage-mode ECG channel, a 532-nW current-mode PPG channel, 76-nW resistive-mode ozone channel, and 12.6-nW peripheral circuits, all at 0.6 V. The total system power consumption including the LED and a custom digital readout IC is 10.98– $15.51~\mu \text{W}$ , which is $41\times $ – $57\times $ less than prior ozone/CVD joint monitoring sensor interface systems.