Analysis and Design of an RC Snubber Circuit to Suppress False Triggering Oscillation for GaN Devices in Half-Bridge Circuits

Wide bandgap devices such as gallium nitride (GaN) devices are being widely used due to their low on-resistance and parasitic parameters that can improve system performance compared to Si mosfets. However, these advantages mentioned above can sometimes lead to unexpected behavior in practical systems, such as false triggering oscillation. False triggering oscillation may cause overshoot, electromagnetic interference, shoot-through, and even device damage, which seriously affects the performance of the system. In this paper, an RC snubber circuit is proposed to suppress false triggering oscillation in a half-bridge circuit, and the design method of the RC parameters is proposed. The proposed oscillation suppression method is simpler, easier to implement, and more effective than the active gate driver. In addition, it can provide guidance for oscillation suppression design in high-order systems. First, the double pulse circuit is used as an example to analyze false triggering oscillation and its high-frequency equivalent circuit is obtained. Then, the RC region is established by scrutinizing the characteristic equations via a root locus method. The RC snubber circuit has better oscillation suppression effect when the RC parameters are within the region rather than outside the region. Finally, the RC region designed by the proposed method is verified by simulation and experiment results, and the proposed method indicates a substantial improvement of the switching characteristics of the controlled device at turn-off.