A Battery-input Hysteretic Buck Converter with 430nA Quiescent Current and 5×104 Load Current Dynamic Range for Wearable Biomedical Devices

This paper presents a battery-input hysteretic buck converter with 430nA quiescent current for wearable biomedical devices. The converter input range is 2.5–4.2 V for rechargeable Li-ion battery and the output is fixed at 1.2 V. To reduce the quiescent power consumption and enhance the power efficiency at light load condition, the PFM controlled buck converter employs a hysteretic comparator with dynamic biasing circuit to reduce the current consumption during idle state. A delay compensation circuit is optimized for the comparator in zero current detector (ZCD) to maximize the overall power efficiency. This converter is implemented in a standard 55nm CMOS BCDLITE process with active circuit area of 0.8mm×0.8mm. Postlayout simulations show the circuit can achieve 5×10
⁴
load current dynamic range in 2 μA– 100 mA, and higher than 85% efficiency is maintained between 10 μA and 100mA with a peak efficiency of 88.6%.