A Gallium-Nitride Point-of-load DC-DC Converter for Space Applications

This paper discusses the evaluation and prototyping of a 12V/3.3V Gallium-Nitride (GaN) point-of-load converter for satellite applications. Traditional power converters used in spacecraft are designed with silicon devices, and there are limitations in efficiency, package parasitic, and thermal management that must be addressed at frequencies above 500kHz. GaN HEMTs have advantages of TID tolerance, shorter turn-on/off time, and lower driving loss. By utilizing GaN HEMTs, switching frequency of 2MHz is selected to trade off volume and efficiency. Low parasitic loop inductance is realized by appropriate layout, and the peak voltage of the switches has been reduced. With the 3-D integration architecture, the junction-to-board thermal resistance has been reduced, and 20A output current is realized in a volume of $15\times 15\times 5.5\mathrm{mm}^{3}$. Calculations, simulations and experimental results are provided to evaluate the performance of the converter.