Analysis of oscillation in bridge structure based on GaN devices and ferrite bead suppression method

For the excellent electrical performance, Gallium Nitride (GaN) new-type semiconductor devices are preferred in high voltage, high frequency and high power applications. However, GaN devices have low on-resistance and the loop layout requires low damping in high frequency loop. These both can lead to voltage and current oscillations under high frequency and even cause uncontrollable oscillations, which limit the application of GaN devices in high frequency occasions especially in bridge circuits. Based on existing literatures, this paper analyzed the generation mechanism of oscillation and proposed two oscillation inducements, which are false turn-on caused by driving oscillation of the passive transistor and Cascode structure. According to the oscillation inducements, several methods are provided and have been verified by simulation and experimental results.