Trade-off between switching loss and common mode EMI generation of GaN devices-analysis and solution

Due to low loss and fast switching capabilities of gallium nitride (GaN) based power devices; there has been a strong interest in the replacement of silicon (Si) devices in power electronics converters for various applications. However, one of the concerns is that the high switching speed (dv/dt and di/dt) of GaN devices will deteriorate the EMI emission of power converters. Hence, this paper studies the common mode EMI emission of GaN based devices by taking a synchronous boost converter as a case study. It will be shown that, exploiting the full switching speed of GaN devices increases the EMI in very high frequency range by up to 10dB comparing to a Si counterpart, while slowing down the switching transition completely offsets the advantage on switching loss. Based on the above observation, two solutions are proposed to mitigate EMI generation of GaN converter without compromising its benefits on low switching loss.