Modeling of Conducted EM Emissions of Synchronous Buck Converters for Different Voltage Conversion Ratios

Large voltage conversion ratios of switching power converters operating at frequencies in the megahertz range are difficult to achieve because of the short pulses of the control signals for the transistor switches, and a multistage topology is a common solution to overcome this problem. A synchronous buck converter based on gallium-nitride FET switches is designed to analyze the effects of different voltage conversion ratios on the conducted electromagnetic (EM) emissions at the input of the converter. The input and output voltage and power levels are set to reproduce the operating conditions of the front-end and load converter in a multistage buck converter topology. The relationship between the generated conducted EM emissions and the voltage conversion ratio of the designed buck converter is approximated by the quadratic regression model. The synchronous buck converter with silicon transistor switches is designed to validate the proposed regression model. The extracted model allows accurate estimation of the conducted EM emissions generated by the buck converter for different voltage conversion ratios.