Investigation of Noise Spectrum and Radiated EMI in High Switching Frequency Flyback Converters

This paper investigates noise spectrums and radiated EMI in high-frequency gallium nitride (GaN) integrated circuit (IC)-based active clamp flyback (ACF) converters. Influential factors for the noise spectrums are investigated, including the switching frequency, dv/dt and waveform symmetry, voltage magnitude, duty cycle, etc. Moreover, in the radiated EMI frequency range, the relationship between spectrum valleys and dv/dt is analyzed. In the investigated GaN IC-based ACF, the voltage spectrums and radiated EMI with high line and low line input voltages are analyzed and investigated experimentally.