Understanding the Impact on parasitic Probing Effects onto the PCB Power-to-Control Crosstalk in Switch-Mode Power Supplies

The Power-to-Control Crosstalk (PCC) in Switch-Mode Power Supplies (SMPS) can be dominated by the parasitic capacitances of the PCB layout. PCC is facilitated by apparently harmless elements of the power converter design, like control chip pinout, the distribution of ground planes, and the setup of the feedback control compensation. This paper shows how to analyze the PCB PCC in power converters by means of FEM simulations, and discusses the effects of probing in measurements, which can mask the increased electromagnetic emissions caused by PCC phenomena.