1 Features
1• Supports signal acquisition of up to 24 phases
• Flexible allocation of 6 LED, 4 PD in each phase
• Simultaneous signal acquisition from different
sensors at different data rates
• Accurate, continuous heart-rate monitoring:
– System SNR up to 108-dB at 16 μA PD current
– Low current for continuous operation on a
wearable device with a typical value: 15 μA for
an LED, 20 μA for the receiver
• Transmitter:
– Supports common anode LED configuration
– 8-Bit programmable LED current with range
adjustable from 25 mA to 250 mA
– Mode to fire two LEDs in parallel with
independent per-phase current control
– Programmable LED on-time per-phase
– Simultaneous support of 6 LEDs for SpO2,
HRM, or multi-wavelength HRM
• Receiver:
– Supports 4 time-multiplexed photodiode inputs
– 2 parallel receivers (two sets of TIA/filter)
– Individual ambient offset subtraction DAC at
each TIA Input with 8-bit per-phase control and
range adjustable up to 255-μA
– Individual LED offset subtraction DAC at each
TIA input with 5-bit per-phase control and 15.5-
μA range
– Close to 100 dB ambient rejection up to 10 Hz
– Noise filtering with programmable bandwidth
– Transimpedance Gain: 3.7 kΩ to 1 MΩ
• Supports external clock and internal oscillator
modes
• Option to acquire data synchronized with a system
master clock
• Automatic cancellation of DC from ambient, LED
• FIFO with 128-sample depth
• I2C interface
• 2.6-mm × 2.1-mm DSBGA, 0.4-mm pitch
• Supplies: Rx: 1.7 V-1.9 V (LDO bypass); 1.9 V-3.6
V (LDO enabled), Tx: 3 V-5.5 V, IO: 1.7-3.6 V

2 Applications
• Optical heart-rate monitoring (HRM) for
wearables, hearables
• Heart-rate variability (HRV)
• Pulse oximetry (SpO2) measurements

3 Description
The AFE44I30 is an analog front-end for optical biosensing
applications, such as heart-rate monitoring
(HRM) and saturation of peripheral capillary oxygen
(SpO2). The device supports up to six switching lightemitting
diodes (LEDs) and up to four photodiodes.
Up to 24 signal phases can be defined and the signal
can be acquired from each phase in a synchronized
manner. The current from the photodiode is
converted into voltage by the transimpedance
amplifier (TIA) and digitized using an analog-to-digital
converter (ADC). The ADC code can be stored in a
128-sample First in, First out (FIFO) block. The FIFO
can be read out using a I2C interface. The AFE also
has a fully-integrated LED driver with an 8-bit current
control. The device has a high dynamic range
transmit-and-receive circuitry that helps with the
sensing of very small signal levels.