Self-Sustained Turn-OFF Oscillation of Cascode GaN HEMTs: Occurrence Mechanism, Instability Analysis, and Oscillation Suppression

This article presents a comprehensive study on the occurrence mechanism, instability analysis, and suppression methods of self-sustained turn-OFF oscillation, which occurs on cascode gallium nitride high electron mobility transistors (cascode GaN HEMTs). In the beginning, the oscillation waveforms are analyzed, which indicate that the occurrence of the oscillation is determined by test circuit instability. Based on the double pulse test, the impact of the load current I-L, dc bus voltage V-DC and gate resistance R-G on the self-sustained oscillation is identified. To investigate the instability of the resonant circuit, a small-signal ac model of the resonant circuit is derived. Based on the model, the influences of various parameters on the self-sustained oscillation are analyzed. The analyses reveal the possible methods which can suppress the oscillation. The effectiveness of the proposed methods is validated by the experimental data and simulation results in the end.

Automated summary

This article presents a comprehensive study on the occurrence mechanism, instability analysis, and suppression methods of self-sustained turn-OFF oscillation that occurs on cascode gallium nitride high electron mobility transistors (cascode GaN HEMTs). It analyzes the oscillation waveforms to determine the occurrence of the oscillation is due to test circuit instability and identifies the impact of load current, dc bus voltage, and gate resistance on the oscillation through double pulse tests. A small-signal ac model of the resonant circuit is derived to investigate its instability and analyze the influences of various parameters on the self-sustained oscillation. The article reveals possible methods to suppress the oscillation, which are validated by experimental data and simulation results.