A 95.1 Efficiency Hybrid Hysteretic Reconfigurable 3-Level Buck Converter With Improved Load Transient Response

Abstract

This article presents a hybrid hysteretic reconfigurable 3-level buck converter for improving load transient response. A reconfigurable 3-level mode operation is proposed to improve the load transient response without the voltage rating issue. The RC feedback network of the hybrid hysteretic control can be adjusted for the optimized transient response. Furthermore, a hysteresis-based quasi-self-balancing scheme, keeping the voltage across the flying capacitor at half the input voltage, is proposed to guarantee stable operation of the proposed converter. Implemented in a 55 nm CMOS, the proposed converter achieves maximum efficiency of 95.1% at an input voltage of 4.2 V, an output voltage of 3.3 V, and a load current of 200 mA. For a load current step of 750 mA, the under/overshoot voltage and settling times are 62/60 mV and 2.48/2.32 mu s, respectively. Compared to the conventional 3-level mode operation, the proposed technique improves the under/overshoot voltage and settling time by 2.21/2.22 and 1.78/1.69 times, respectively.