The Effect of Differential Driver Asymmetries on Common-Mode Frequency Spectrum

A frequency spectra determination of the common-mode signal due to the differential driver asymmetries is presented. The analytical expression for the Fourier series is developed and the evaluations for different dependencies are introduced. The effect of the skew time and amplitude imbalance is shown in a parameter study. From the general analytical solution a compact expression for small amplitude imbalances is deduced. This allows to study the influence of the driver time skew on the resulting common-mode signal, which is the source of unwanted electromagnetic radiation. It is found that for realistic driver parameters, the driver skew is the most responsible.