Forward wave analysis of vertical distribution of power supply noise in multilayer PCB

Power supply noise generated by integrated circuits is one of the major sources of EM radiation from PCBs. The reduction of power supply noise can be realized by means of devices that bypass the current among power supply planes, such as bypass capacitors, ground vias and so on. In a previous work the effect of current bypass devices on the far field radiation from multilayer PCBs was very efficiently estimated by means of a new technique called forward wave analysis. In this work it is shown that forward wave analysis can be used also to study the vertical distribution of the power supply noise in multilayer PCBs. This allows to understand some important noise propagation mechanisms and to take low-cost countermeasures at early stage of PCB design.