Analysis of conducted and radiated noise propagation using comprehensive electromagnetic model of power MHz-switching circuit

In this paper, we describe the simulation results of electromagnetic (EM) noise generated by fast switching circuits with gallium nitride (GaN)-based power devices. The frequency ranges of the EM noise extend to several hundred MHz because the GaN devices possess low parasitic capacitance. Therefore, we analyze both the conducted noise of the switching circuits and the radiated noise from the circuit. In the simulation, a comprehensive model that includes packages of the GaN-based power devices, a board of the switching circuits and parallel cables is used. To analyze the conducted noise, we propose a novel mixed-mode S-parameter, which expresses the transmission properties from the noise source in the power device to the terminal point of the parallel cables. At the terminal point, common-mode (CM) and differential-mode (DM) conducted noise are calculated. The simulation results show that the radiated noise strongly correlates with the CM conducted noise. As far as authors know, this is the first report that shows the relationship between the conducted and radiated noise for a MHz switching circuit.