Ultra-low-power AFE created for optical bio-sensing applications

Texas Instruments AFE44I30 Ultra-Low-Power Integrated Analog Front End is intended for optical bio-sensing applications, such as heart-rate monitoring and saturation of peripheral capillary oxygen (SpO2).

The device supports up to six switching LEDs and up to four photodiodes. Up to 24 signal phases are able to be defined, and the signal obtained from each phase in a synchronised manner. The current from the photodiode is converted into a voltage by the TIA and digitised employing an ADC. The ADC code can be stored in a 128-sample FIFO block. The FIFO can be read out using an I2C interface.

The device comprises a fully-integrated LED driver with an 8-bit current control. The device provides a high dynamic range transmit-and-receive circuitry that assists with sensing of very small signal levels.

Typical applications include optical heart-rate monitoring for wearables, hearables; heart-rate variability; and pulse oximetry (SpO2) measurements.