Switching Behavior of Cascode GaN Under Influence of Gate Driver

With high-frequency, low power dissipation and high-efficiency characteristics, Gallium nitride (GaN) power devices are of significant benefit in designing high-speed motor drives, as they improve performance and reduce weight. However, due to the cascode structure, coupling with the parasitics in gate driver and power circuits, power converters based on cascode GaN are prone to overshoot and oscillate on switching waveforms, which may lead to serious EMC problems, or even device breakdown. The complicated structure of cascode GaN device makes the gate driver design comparatively complex. An analytical model of the switching process considering gate driver parameters is proposed in this article. The influence of gate driver parameters on switching behavior is investigated from the perspective of switching speed, waveform overshoot, and power loss. Trade-offs among overshoot, switching speed, and power loss are discussed; guidelines to design gate driver parameters are given.