Efficiency and weight reductions have been a focus in the radiation hardened power converter industry for many years. The only option for a switching device has been the radiation hardened MOSFET. The MOSFET has a limited number of suppliers and is often challenging to acquire. Not only is availability scarce, but the cost, performance, and size also make it laborious to design an efficient compact power supply. With the recent offerings of the GaN FETs this focus has become a reality.
This paper will focus on the 200V GaN device that is used in a 100V input DC-DC converter. The data referenced comes from VPT’s SGRB Series of power conversion products. Currently the smallest 200V power radiation hardened MOSFET is offered in an SMD – 0.5 package which is 7.52 mm x 10.16 mm in size. The on-state resistance ranges from 0.13 Ω - 0.4 Ω. The current 200V Gan FET offered from EPC Space is 3.9 mm x 5.7 mm, with a 0.028 Ω on state resistance. The radiation hardened MOSFET is almost 3.5 times larger than the GaN FET and the MOSFET has more than 4.5 times the on-state resistance. One of the highest loss components in the power supply design is always the switching device. Using this transformative technology allows power converter efficiencies to take a drastic leap forward while reducing the overall size and weight.