1 Features
Supports signal acquisition of up to 16 phase sets
Supports up to 32 LEDs, 4 PDs
Flexible allocation of LEDs, PDs in each phase
Simultaneous signal acquisition from different
sensors at different data rates
Accurate, continuous PPG monitoring:
– Low current for continuous heart-rate
monitoring on a wearable device with a typical
value: 15 μA for an LED, 15 μA for the receiver
– Peak system SNR of 115 dB
Transmitter:
– 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 32 LEDs for SpO2,
Multi-Wavelength HRM, and Spectroscopy
Receiver:
– Supports 4 Time-Multiplexed PD Inputs
– 4 parallel receivers (4 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 9-bit per-phase control and 64-
μA range
– Digital ambient subtraction at ADC output
– Noise filtering with programmable bandwidth
– Transimpedance gain: 3.7 kΩ to 1 MΩ
Supports external clock or internal oscillator
Option to acquire data synchronized with a system
clock
Automatic cancellation of DC from Ambient, LED
FIFO with 256-sample depth
SPI™ interface/ I2C interface
2.6-mm × 2.6-mm DSBGA, 0.4-mm Pitch
Supplies: Rx:1.7 - 1.9 V (LDO Bypass); 1.9 - 3.6 V
(LDO Enabled), Tx: 3-5.5 V, IO: 1.7-RX_SUP

2 Applications
• Optical Heart-Rate Monitoring (HRM) for
wearables, hearables
• Heart-Rate Variability (HRV)
• Pulse Oximetry (SpO2) measurements
• Optical Spectroscopy

3 Description
The AFE4460 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 32 switching lightemitting
diodes (LEDs) and up to four photodiodes
(PDs). The AFE has two LED drivers each with 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. Up to 16
signal phase sets can be defined, each phase
set comprising a combination of LED and Ambient
phases. Low noise offset DACs at the receiver inputs
can be automatically controlled to cancel DC from
Ambient and LED light. The current from each of
the 4 PDs in each phase is converted into voltage
by TIAs, filtered, and then digitized using a common
ADC. The ADC code can be stored in a 256-sample
FIFO block. The FIFO can be read out using a SPI or
I2C interface.