Impact of asymmetrical shape for trapezoidal signal on ICs spectral emission envelope

To respect the conducted emission limits in the standards, some solutions were already presented about hard switching power devices. The main solution consists in playing on rise time (τr) and fall time (τf) which are the root cause of harmonic contents. This paper theoretically shows the effect of asymmetric and symmetric shape of trapezoidal signal on spectral emissivity. An original chart was performed to quantify rising and falling times variations impact. The contribution of other parameters of the signal will be considered and a tool to help designers to anticipate all these modifications will be presented.