Analysis of dominant frequency ranges for various modes of EMI generated by switching converters

EMI measurement and separation of the Common and the Differential Mode components of noise is necessary to design proper filter to mitigate EMI. It is also important to determine, which component is dominant in a particular frequency range so that the power supply filter may be modified to suit the regulatory limits. Fourier series Analysis is used in this paper to determine the area of dominance of various noise modes obtained from experimental results reported in literature.