Driving Techniques for GaN Power HEMTs

One of the challenges in the application of GaN power HEMTs is designing the gate driver for optimal performance of the transistors. GaN transistors can switch much faster than silicon (Si) devices and require more precise control on timing. Controlling the ringing oscillation during each switching transient is essential for improved efficiency and electromagnetic compatibility (EMC). In this thesis, two driving techniques are examined. A dynamic gate drive technique is examined for driving cascode GaN devices in a flyback converter using a custom gate driver originally designed for silicon power MOSFETs. A reduction in conducted electromagnetic interference (EMI) of 6dB at 80 MHz is observed. Optimal deadtime is investigated for a class D audio output stage utilizing GaN enhancement HEMTs using commercial gate drivers. Experimental results suggest that a proper selection of deadtime can minimize the losses, EMI, and total harmonic distortion (THD) of the amplifier.M.A.S