SBAT014 October 2023 AFE4432 , AFE4460 , AFE4950
Applications like optical heart rate and SpO2 monitoring are based on the principle of Photoplethysmography (PPG). The primary challenges in PPG signal acquisition on a wrist-worn variable are: (i) small sensor size, (ii) relatively weak signal on wrist (low perfusion index), and (iii) interferers like ambient light and motion artifacts. TI’s signal chain for PPG signal acquisition has 3 unique characteristics that help achieve excellent signal quality even in the most challenging conditions: (i) high gain transimpedance amplifier (TIA) to improve the SNR, (ii) DC offset cancellation DAC at the input, and (iii) noise reduction filter to reduce the optical noise bandwidth. These unique features help achieve excellent dynamic range at extremely low power consumption.
Heart Rate Monitoring
SpO2 Monitoring
Block DiagramRecommended Parts
| Device | Description |
|---|---|
| AFE4432 | Ultra-small, ultra-low-power, high-SNR, integrated analog front ends (AFE) for wearable optical biosensing with FIFO |
| AFE4460 | High-SNR, ultra-low-power, integrated AFE for wearable optical biosensing with FIFO |
| AFE4950 | Ultra-small integrated AFE for wearable optical heart-rate monitoring and SpO2 |
| AFE4500 | Integrated analog front end (AFE) for bioimpedance analysis and electrical and optical biosensing |
TI Resources
- Optical Heart Rate Monitoring (OHRM) on Wearables Application Brief
- Measuring Oxygen Saturation (SpO2) on Wearables Application Brief
- DC Estimation for SpO2 using TI AFEs Application Note (under NDA)