A 400W, 99.3% Efficient GaN Buck-Boost Converter

This paper presents a high-efficiency high-power density 500kHz gallium nitride (GaN) based buck-boost converter. State-of-the-art silicon-based buck-boost converters are limited by the poorer device figure of merit (FOM) of silicon technology, namely these converters suffer from large capacitance related switching losses which limit the switching frequency and deteriorate the efficiency and power density. GaN power devices with much better FOM provide lower conduction loss and switching loss at the same time even at elevated switching frequencies. However, quantitative benefits of replacing Si-MOSFETs with GaN FETs are not well-defined in many cases. The focus of this paper is to quantify the impact in a buck-boost converter which is becoming increasingly important due to the proliferation of battery-powered electronics systems. Experimental results are presented in order to show the superior performance of the GaN-based converter in comparison to the state-of-the-art Si-MOSFETs converters. The experimental results show very high efficiency (up to 99.3%) in a wide range of operations and high-power density. The prototype achieves a power density of 110W/cm ³ using IHLP6767GZ01 inductor and 35W/cm ³ using IHLP8787MZ5A inductor.