A 40-nA Quiescent Current Buck Converter With ACC/AOT Dual-Mode Control and Fast-Transient Response for IoT Application

A dual-mode ultra-low quiescent current DC-DC buck converter is proposed to achieve high efficiency over a wide load range from $1 \mu \mathrm{~A}$ to 100 mA. The circuit employs adaptive clock control (ACC) for light load and adaptive on-time control (AOT) for heavy load. Additionally, the circuit introduces a load transient enhancing comparator to achieve minimal voltage undershoot, along with fast recovery time. The converter is implemented in a 180 nm process and operates with an input voltage of 2.4 V to 3.3 V and an output of 1.5 V. It achieves over 90% efficiency across full load range, with a peak efficiency of 97.3% at 2.4 V input. The total quiescent consumption is 40 nA and it achieves an undershoot voltage of 43 mV and a recovery time of $5.3 \mu \mathrm{~s}$ when the load current steps from $10 \mu$ A to 100 mA.