Direct 48-/1-V GaN-Based DC–DC Power Converter With Double Step-Down Architecture and Master–Slave AO²T Control

Abstract

In modern power delivery systems, there has been an up-rising trend of migrating conventional two-stage dc-dc power conversion architecture to a single-stage one, in order to accomplish better efficiency and power density. In response to such a trend, this article presents a gallium nitride (GaN)-based power converter design that achieves direct 48-/1-V dc-dc power conversion with a single-stage double step-down (DSD) architecture. Operating at 2 MHz, it pushes the equivalent minimum duty ratio to a record low level of 2.1%. In order to improve closed-loop regulation, an adaptive ON- and OFF-time (AO <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> T) control with elastic ON-time modulation is proposed for both steady-state and transient response enhancement. For reinforced reliability in the dual-phase operation, a master-phase mirroring technique enables adaptive master-slave phase operation, accomplishing automatic phase current balancing. An IC prototype is implemented on a 180-nm high voltage (HV) bipolar, CMOS DMOS (BCD) process, with an active die area of 1.46 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . It achieves peak efficiencies of 85.4%, 79%, and 56.8% at 100 kHz, 250 kHz, and 2 MHz, respectively.