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A Low-Power, Auto-DC-Suppressed Photoplethysmography Readout System with Differential Current Mirrors and Wide
Chanyoung Son1, Seok-Tae Koh2, Hyuntak Jeon1
1School of Semiconductor Engineering, Chungbuk National University (CBNU), Cheongju 28644, Republic of Korea.
Micromachines
|April 26, 2025
Summary
This study introduces a low-power photoplethysmography (PPG) system for wearables. It efficiently processes PPG signals with minimal power, enabling advanced health monitoring.
Area of Science:
- Biomedical Engineering
- Integrated Circuit Design
Background:
- Wearable health monitoring requires efficient and accurate biosignal acquisition.
- Existing photoplethysmography (PPG) systems often face challenges with power consumption and DC component interference.
Purpose of the Study:
- To develop a low-power, high-performance PPG readout system for wearable health devices.
- To simplify PPG system design by eliminating DC cancelation loops.
Main Methods:
- Implemented a differential current mirror (DCM) to convert single-ended PPG currents to differential voltages, suppressing DC components.
- Utilized a wide common-mode input range (WCMIR) SAR ADC for accurate analog-to-digital conversion of differential signals.
- Designed and simulated the system in a 0.18 µm CMOS process.
Main Results:
- Achieved a low power consumption of 9.6 µW.
- Demonstrated over 60 dB DC dynamic range.
- The system occupies a small area of 0.30 mm², suitable for multi-channel applications.
Conclusions:
- The developed low-power PPG readout system offers an efficient and scalable solution for wearable health monitoring.
- The DCM and WCMIR SAR ADC approach simplifies design and enhances performance for portable biomedical sensing.
