A Power Management Unit Design for a Wearable ECG Application

Power efficiency and stability are critical for wearable ECG application. The paper presents a Pulse-Width-Modulation (PWM) voltage type DC-DC converter, which has a small area of 0.32 mm2 on active chip, output voltage range of 0.8V to 3.5V, output power up to 7.5 mW, and peak efficiency of 95.8%. The simulation results show that the output voltage of the system is 1.8V, the output current is 4mA, the ripple voltage is 13mV and the efficiency is 86.1%, which meets the requirements of a presented system. The circuit will be fabricated by the SMIC in the near future with $0.18\ \mu\mathrm{m}$ Bipolar-CMOS-DMOS (BCD) process.