Texas Instruments – Ultra-small integrated AFE for multisensor wearable optical heart-rate monitoring

Texas Instruments AFE4420 is an analog front end for optical biosensing applications, such as heart rate monitoring and peripheral capillary oxygen saturation. The device supports up to four switching LEDs and up to four photodiodes. A maximum of 16 signal phases can be defined, and signals can be collected from each phase in a synchronized manner and stored in a FIFO block of 128 samples. The FIFO can be read via the I2C or SPI interface. The AFE also features a fully integrated LED driver with 8-bit current control. The device has high dynamic range transmit and receive circuits to help detect very small signal levels.