Ultra-low-power integrated AFE for wearable optical, electrical biosensing

14-08-2017 | Texas Instruments | 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.

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