High frequency model and parameter sensitivity analysis of EMI filter´s characteristic in switched mode power supply

EMI filters are commonly used to suppress the EMI in SMPS, but their frequency characteristics, especially in the high frequency band, are usually much worse in a real system than the design expectation. The paper conducts a study on an EMI filter´s HF model, and then makes an analysis of the sensitivity of the filter frequency characteristic to parameters based on the rather accuracy model; the results show that they may be helpful for performance design optimization of a filter and its conducted EMI debugging.