Prospects and limits of common- and differential-mode separation for the filter development process

A common way to describe conducted electromagnetic disturbances is to separate the measured noise voltages into common- and differential-mode. To design an appropriate EMI line filter the noise impedance has to be considered during the development process. The described method uses the practical approach to determine the common- and differential- noise impedances to calculate the filter attenuation up to 108 MHz for automotive applications. This article gives an overview on how to use disturbance decomposition and shows the limits of the mode separation procedure for the filter development process.