A wide operating range, fast settling, and accurate current sourcing LED driver for PPG (Photoplethysmography) sensor applications is presented. Proposed NMOS resistor array and RC-time constant based calibration circuit precisely control target LED driving current with less than 0.5% error over process variations. For the fast settling of pulse-width modulation (PWM) based boost converter loop, pulse-width prediction technique is proposed which greatly improves the settling time. The driver circuit is designed in 180-nm CMOS process, supporting green/red/infrared LED driving voltage, 0.1-100% duty-cycling and 1-100 mA driving current.
This research was supported by National R&D Program through the National Research Foundation of Korea (NRF) funded by Ministry of Science and ICT(RS-2023-00258227). The EDA tools were supported by IDEC.
