Active Conducted EMI Suppression in GaN Switching Power Circuits

Abstract

With the introduction of fast switching GaN power transistors, electromagnetic interference (EMI) has risen to record level in switching power circuits. To mitigate the challenge, this paper discusses recent active EMI suppression circuit solutions that are tailored for high switching frequency GaN power circuits. The focus is on the utilization and implementation of spread-spectrum modulation (SSM) techniques. Specifically, the author reviews two recent developments on continuous and random SSM (C-RSSM) approaches, using a novel and efficient Zener diode and a Markov-chain random signal generator respectively. The efforts are made on not only EMI suppression and but also fundamental power voltage regulation. Following the C-RSSM solutions, a multi-rate SSM (MR-SSM) approach is discussed, which minimizes spectrum overlaps and is capable of zero-voltage switching (ZVS) operation for efficiency improvement.