A Low-Power Dynamic-Range Relaxed Analog Front End for Photoplethysmogram Acquisition*

This paper presents a low-power analog front-end that enables photoplethysmographic signals acquisition, the dynamic range for AC component exaction is relaxed with simple high-pass implementation. The chopping modulation ensures the low-noise operation. The circuit is fabricated in a 0.18-um CMOS technology. Measurements show that the consuming current is approximately 72 uA at a supply of 2.5 V. The circuit achieves a input noise of 6.45 $\mathrm{pA}/\sqrt{Hz}$. The calibred algorithm is implemented by means of MCU, and the demonstration that is compared with the Fluck Simulator used as the reference shows the heart rate is accurately detected, and the error of the measured blood oxygen saturation is less than 1.5%.