A 15MHz GaN FET AZVT Buck Converter that Achieves 7.2-point Efficiency Increase at Heavy Load

This paper presents an adaptive zero-voltage transition (AZVT) GaN FET buck converter operating at 10MHz to 15MHz while zero voltage switching (ZVS) can be achieved at various input voltage VIN, output voltage
$V$
OUT
, and load current I
LOAD
conditions. To achieve accurate turn-on timing of the auxiliary GaN FET for high-side GaN FET ZVS, high-side power rail ZVS detector circuit and turn-on/off timing controller are proposed. The proposed controller circuits and GaN FET driver are implemented in 0.25μm HV BCD process. The proposed AZVT converter achieves maximum efficiency of 89.3% at VIN=12V,
$V$
OUT
=5V, I
LOAD
= 1.1A, and
$f$
sw=10MHz. The proposed AZVT converter shows 7.2-point efficiency increase at maximum from the conventional hard-switching converter at VIN=12V,
$V$
OUT
=3.3V,
$I$
LOAD
=1.5A, and fsw=15MHz. This corresponds to 600mW power saving.