A 240-nA Quiescent Current, 95.8% Efficiency AOT-Controlled Buck Converter With A2-Comparator and Sleep-Time Detector for IoT Application

An ultralow-quiescent current dc-dc buck converter with a single controller is presented to achieve high efficiency over a wide load range for Internet of Things application, which is achieved by utilizing adaptive ON-time control topology. An on-demand modulation strategy and sleep-time detector are proposed to attain sub-mu A quiescent current consumption under ultralight load condition. The adaptive-bias and adaptive-gain (A(2)) comparator is presented to improve the loop stability caused by the inherent propagation delay of the low-power comparator. Moreover, a novel ON-time generator is proposed to fix the switching frequency in continuous conduction mode. The proposed buck converter was implemented by using a 0.18-mu m CMOS process with an area of 1.092 mm(2). It achieves a peak efficiency of 95.8% and >90% efficiency from 10 mu A to 300 mA. A 240-nA quiescent current, including bandgap voltage and current reference, is achieved. With a low output ripple of less than 20 mV, the input voltage range and regulated output voltage are 2.1-5.5 and 1.8 V, respectively.