Practical PCB Design Considerations for GaN HEMTs Based Isolated DC-DC Converter

This paper proposes improved PCB design techniques for converters using Gallium Nitride High Electron Mobility Transistors (GaN HEMTs). An isolated DC-DC converter designed for high-temperature (>150 °C) applications-such as defense, oil and gas, etc.- is considered as the test case for validating the proposed concepts. The primary focus of this paper is to address the challenge of reducing voltage spikes in the drain-to-source voltage (V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</inf>) by minimizing parasitic elements, thereby improving voltage quality in high power density GaN HEMT designs. The proposed ‘closed-form’ layout for a half-bridge configuration effectively decreases the parasitic inductances, a significant stride in enhancing voltage stability and overall device performance.Ansys (Q3D analysis) simulations, for the conventional designs and the proposed closed-form layout are done and results are compared. These simulation results are validated through hardware experiments, providing comprehensive confirmation of the design's effectiveness. It is shown that the proposed closed-form layout of GaN HEMT presents a substantial reduction in the V<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</inf> spikes.