An 86% efficiency Multi-Phase Buck Converter using Time-Domain Compensator and Adaptive Dead-Time Control for DVS Application

Abstract

A high-frequency switching, multi-phase buck converter capable of nanosecond-scale Dynamic Voltage Scaling (DVS) is reported in this work. The proposed converter employs a time-domain compensator using VCOs and Voltage Controlled Delay Lines (VCDL). The closed loop bandwidth of the converter is scaled with the active number of phases by adjusting the control parameters in the compensator. In addition, this paper also proposes a digital-intensive adaptive dead-time controller that helps to minimize unwanted body diode conduction/short circuit losses occurring in the power switches. A test chip fabricated in 55nm CMOS technology generates an output voltage of 0.6-1.2V from a 1.8V supply. A thin-film magnetic inductor with an inductance of 38nH and a quality factor of 14 along with a 10nF capacitor, filters the switching pulses at the output. Proposed design achieves a peak efficiency of 86% and delivers an output power up to 1.8W. This work is able to produce higher output current up to 1.5A and a larger output slew-rate of >4Vµ/s than the state-of-the-art while switching at only 50MHz.