A Multi-Channel Low-Power LED Driver Circuit for PPG

This paper introduces a precision current rudder type LED constant current driver with a 8-Bit dynamic range adjustable DAC, and a 2-bit programmable full scale option. It can be flexibly configured to meet the requirements of LED brightness for photoelectric volume pulse acquisition in different cases. The 180nm CMOS process realizes current configuration in the 0–128mA range, with a single 1 LSB input resulting in a 125–500μA current change. The LED drive current amplitude is controlled by the combination of binary and thermometer code. This work achieves a system power consumption of 0.386 mW through low-voltage logic circuits and low-power operational amplifiers. It adopts Chopper Offset-Stabilized Opamp to solve the problem of offset and noise.