Ultra-low-power integrated AFE for wearable optical, electrical biosensing
Test & Measurement
The Texas Instruments AFE4900 device is an AFE for synchronized ECG, PPG signal acquisition. The device can also be used for optical bio-sensing applications, such as HRM and SpO2. The PPG signal chain supports up to four switching LEDs and up to three photodiodes (PDs).
The LEDs can be switched on using a fully integrated LED driver. The current from the photodiode is converted into voltage by the TIA and digitized using an ADC. The ECG signal chain has an INA with a programmable gain that interfaces to the same ADC. A RLD amplifier set can be used to the bias for the ECG input pins.
AC and DC lead-off detect schemes are supported. The ADC codes from the PPG and ECG phases can be stored in a 128-sample FIFO block and read out using either an I2C or a SPI interface.