Suppression Strategy for Oscillation between Two Paralleled GaN-HEMTs Based on Harmonics of Switching Surge

This paper presents guidelines for suppressing oscillations between paralleled GaN-HEMTs focusing on the harmonics of switching surges. In recent years, false triggering due to oscillation between paralleled GaN-HEMTs has become a practical issue. To suppress this oscillation, it is essential to reduce the noise that triggers the oscillation. This noise is caused by switching surges and inductance imbalances in the PCB layout. However, as more GaN-HEMTs is connected in parallel, it becomes difficult to avoid inductance imbalance in the PCB layout. This paper reveals that the harmonics of the switching surge trigger oscillation in paralleled GaN-HEMTs. These harmonics are caused by nonlinearity of the drain-source capacitance. Based on this insight, we propose parasitic inductance design considering harmonics of switching surge. Experiments have confirmed the transition from switching surges to oscillation. Furthermore, we confirmed through simulation that oscillation between paralleled GaN-HEMTs can be suppressed by designing the resonant frequency between GaN-HEMTs to avoid the harmonics of the switching surge.