A 96% Efficient High-Frequency DC–DC Converter Using E-Mode GaN DHFETs on Si

III-Nitride materials are very promising to be used in next-generation high-frequency power switching applications. In this letter, we demonstrate the performance of normally off AlGaN/GaN/AlGaN double-heterostructure FETs (DHFETs) using a boost-converter circuit. The figures of merit of our large (57.6-mm gate width) GaN transistor are presented:
$R_{\rm ON} \ast Q_{G}$
of 2.5
$\Omega\cdot\hbox{nC}$
is obtained at
$V_{\rm DS} = \hbox{140\ V}$
. The switching performance of the GaN DHFET is studied in a dedicated high-frequency boost converter: both the switching times and power losses are characterized. We show converter efficiency values up to 96.1% at 500 kHz and 93.9% at 850 kHz at output power of 100 W.