A fast-transient-response hybrid buck converter with automatic and nearly-seamless loop transition for portable applications

This paper presents a fast-transient-response hybrid buck converter (HBC) which consists of a voltage mode PWM switching converter with Type III compensation and two auxiliary linear regulators for portable applications. With techniques of hysteretic load transient detection and adaptive duty ratio compensation, the proposed HBC achieves automatic and nearly-seamless loop transition during load transient to achieve small voltage dip and short recovery time. The auxiliary linear regulators can be automatically deactivated in the steady state such that the power efficiency of the switching converter is not compromised. Experimental results of a 0.13-μm CMOS prototype with 10 MHz switching frequency show that, compared with the conventional design, the proposed HBC reduces the voltage dip from 145mV to 55mV and the recovery time from 7.0μs to 1.5μs for a 300mA load current step-up within 20ns.