A 285-nA Quiescent Current, 94.7% Peak Efficiency Buck Converter With AOT Control for IoT Application

An ultralow quiescent current dc-dc buck converter based on adaptive on-time (AOT) control is presented in this article. To minimize the energy wastage of the dc-dc buck converter circuit when the Internet-of-Things (IoT) device is in standby mode, a control loop with nano-ampere quiescent current is proposed in this converter. To reduce the quiescent current consumed by the voltage reference and improve its line sensitivity (LS), the voltage reference in the proposed converter is preregulated and based on the subthreshold CMOS implementation, with a quiescent current of only 20 nA. Meanwhile, for purpose of maintaining high efficiency of the converter under the ultralow load, an adaptive comparator based on the dynamic bias mode selection circuit is proposed, which converts the load conditions into time information and switches the bias current and gain of the comparator under ultralow loads, and the quiescent current of the comparator is only 65 nA. The proposed converter is implemented in a 0.18- $\mu $ m BCD process with an area of 1.35 mm2. Experimental results show that the converter has a minimum quiescent current of 285 nA, maintains more than 80% conversion efficiency over a load range of $10~\mu $ A–300 mA and a peak efficiency of 94.7%, and has an output of 0.9–4.8 V over a supply condition of 2–5.5 V.