Modeling And Numerical Analysis Of High-speed PCB Radiation Control

With the high-speed printed circuit board(PCB) layers and frequency increasing, the radiation control problems become more and more serious, and need to be solved urgently. It not only affects the function of multilayer board, but also affects the surrounding of electronic system.It may generate radiation interference to electronic system and harm to human health and thus does not satisfy the EMC test standards. This article is mainly to study from two aspects of radiation. Firstly, when the return current flows through the power / ground plane of power distribution network of the multilayer PCB, and the frequency of the signal approach or reach the resonant frequency of board as the resonant cavity structure of power/ground plane, it may cause resonance between the power / ground plane, and lead input impedance to reach maximum, moreover signal can not past the plates, and current return path is blocked, so it will radiate from the edge of multilayer printed circuit board(PCB)in the form of electromagnetic waves. Otherwise there is also a radiation problem caused by noise that introduced into the power / ground planes.Based on the control of noise radiation in power/ground plane in this paper, it adopt electromagnetic band gap(EBG) structure which is the hot spot of the noise suppression research, namely the segmentation method of power/ground plane. As the high impedance surface of EBG structure, inhibited the formation of surface current, thus reduced the radiation of PCB. Unlike in the most papers, using EBG structures on the entire power/ground planes,that may severely damage the board’s power integrity. In the analysis effection of noise suppression, this paper used equivalent circuit model to model and HFSS to calculate S parameters. This paper arranged segmentation unit or EBG structure around the signal via from the perspective of local. Segmentation unit, EBG structure, via, and power ground plane resonator structure were modeled by electromagnetic field, the input impedance and the radiation field intensity was calculated by the Boundary Element Method. Than taking EBG of PCB to compare with no use this structure of the PC board. Finally compared with the results of three-dimensional full-wave electromagnetic simulation software ansys simulation to verify the effectiveness of this method.When the current return path between the power/ground plane is not continuity, studying to arrange SMT(Surface Mount Technology) decoupling capacitor around the via between power/ground plane plate that provide the current a reasonable return path, making the signal smooth transmission between the plates, thus the PCB radiation can be under control. Using method which combine characteristic of electromagnetic field and circuit, model via, decoupling capacitor and power/ground plane cavity structure, then use boundary element method to calculate results. What`s more,analysis how to decorate decoupling capacitors, and how much decoupling capacitor decoupling is better.