The component density in modern designs is becoming ever greater. From an EMC point of view, many PCB designs today are therefore created as multilayer designs with separate layers for the supply of the components. This inevitably raises the question of how to connect e. g. filter components to the reference potential. How many vias are actually useful and what arrangement should be chosen for them? How much does the capacitance value and the impedance of the ferrite change with voltage and current and what does this mean for my filter characteristic? These questions will be investigated by means of various measurements and simulations.