高速PCB輻射控制的建模與數(shù)值分析
發(fā)布時間：2019-02-20 09:33
【摘要】：隨著高速印制電路板(PCB)的層數(shù)以及頻率越來越高的趨勢,其輻射影響控制問題越來越嚴重,也是亟待需要解決的問題。它不僅影響到多層板自身元器件的功能,還會對它周圍的電子系統(tǒng)產生輻射干擾及對人的健康產生危害從而不滿足電磁兼容測試標準。本文主要從引起高速PCB輻射的兩個方面來研究。其一在多層印制電路板(PCB)電源分布網(wǎng)絡中,由于其電源/地平面構成的諧振腔結構,當返回電流經(jīng)過電源/地平面時,信號的頻率接近或者達到板的固有諧振頻率時,引起電源/地平面之間的諧振,導致輸入阻抗Zpp達到最大值。信號因而在板之間傳輸不過去,電流的返回路徑受到阻礙,將以電磁波的形式從多層印制電路板(PCB)邊緣輻射出去。還有一種是引入到電源/地平面的噪聲所引起的輻射問題。本文針對電源/地平面的噪聲輻射的控制,采取現(xiàn)在噪聲抑制研究熱點的電磁帶隙(EBG)結構,即分割電源/地平面的方法。利用電磁帶隙結構的高阻抗表面,抑制表面電流的形成的原理,隔離噪聲,從而降低了PCB的輻射。不同于大多數(shù)論文中,在整個電源/地平面采用EBG結構嚴重破壞了板的電源完整性,分析噪聲抑制效果采用等效電路模型進行建模和HFSS計算S參數(shù)。本文則從局部的角度在信號過孔周圍布置分割單元或者EBG結構,用場的分析方法對分割單元、EBG結構、過孔和電源/地平面構成的諧振腔結構進行了建模和用邊界元法對輸入阻抗和輻射場強進行了計算,并與沒有采用這種結構的PC板進行了對比。采用場的方法使得結果精確度更高,邊界元法則只需要對邊界進行離散,無需求解區(qū)域內部電場值,且適用于任何形狀的電源/地平面結構。最終與三維電磁仿真軟件ANSYS全波仿真結果進行了對比,驗證了采用此方法的有效性。針對電源/地平面之間的電流返回路徑不連續(xù)性,研究通過過孔周圍布置SMT(貼片式)去耦電容為流經(jīng)電源/地平面板的電流提供一個合理的返回路徑,使信號能順利的在板間傳輸,從而PCB板輻射得到控制。用場路結合的方法對過孔、去耦電容和電源/地平面構成的諧振腔結構進行建模和邊界元法進行數(shù)值計算。分析了怎樣去布置去耦電容,計算了布置多大的去耦電容才能使得去耦效果更佳。
[Abstract]:With the increasing number of layers and frequency of high speed printed circuit board (PCB), the problem of radiation impact control is becoming more and more serious, which needs to be solved urgently. It not only affects the function of multilayer board itself, but also causes radiation interference to the electronic system around it and endangers human health, which does not meet the test standard of electromagnetic compatibility (EMC). This paper focuses on two aspects of high-speed PCB radiation. First, in the multi-layer printed circuit board (PCB) power distribution network, because of the resonant cavity structure formed by the power supply / ground plane, when the return current passes through the power / ground plane, the signal frequency is close to or reaches the inherent resonant frequency of the board. Resonance between the power supply and ground plane results in the maximum input impedance Zpp. As a result, the signal can not be transmitted between the boards, and the return path of the current is hindered, which will radiate from the (PCB) edge of the multilayer printed circuit board in the form of electromagnetic waves. Another is the radiation problem caused by noise introduced into the power / ground plane. In order to control the noise radiation of the power / ground plane, this paper adopts the electromagnetic bandgap (EBG) structure, which is a hot research topic of noise suppression, that is, the method of dividing the power supply / ground plane. The high impedance surface of the electromagnetic band gap structure is used to suppress the formation of the surface current and to isolate the noise so as to reduce the radiation of PCB. Different from most papers, using EBG structure in the whole power / ground plane seriously destroys the power integrity of the board. The noise suppression effect is modeled by equivalent circuit model and the S parameter is calculated by HFSS. In this paper, partitioning units or EBG structures are arranged around the signal passing holes from a local point of view. The method of field analysis is used to analyze the segmentation units and EBG structures. The input impedance and radiation field strength are calculated by boundary element method, and compared with those of the PC-board without this kind of structure, which is composed of perforated cavity and power supply / ground plane structure, and the boundary element method is used to calculate the input impedance and radiation field strength of the resonator. The accuracy of the results is improved by using the field method. The boundary element rule only needs to discretize the boundary, does not need to solve the electric field value inside the region, and is suitable for any power / ground plane structure of any shape. Finally, the results are compared with the full wave simulation results of 3D electromagnetic simulation software ANSYS, and the effectiveness of the proposed method is verified. In view of the discontinuity of the current return path between the power supply and the ground plane, a reasonable return path for the current flowing through the power supply / flat panel is studied through the arrangement of SMT (sticker type) decoupling capacitors around the hole. The signal can be transmitted smoothly between plates, and the radiation of PCB board can be controlled. The field circuit method is used to model the resonant cavity structure which is composed of perforating, decoupling capacitance and power / ground plane, and the boundary element method is used to carry out the numerical calculation. This paper analyzes how to lay out decoupling capacitors, and calculates how much decoupling capacitors are arranged to make the decoupling effect better.
【學位授予單位】：集美大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN41
本文編號：2427053
[Abstract]:With the increasing number of layers and frequency of high speed printed circuit board (PCB), the problem of radiation impact control is becoming more and more serious, which needs to be solved urgently. It not only affects the function of multilayer board itself, but also causes radiation interference to the electronic system around it and endangers human health, which does not meet the test standard of electromagnetic compatibility (EMC). This paper focuses on two aspects of high-speed PCB radiation. First, in the multi-layer printed circuit board (PCB) power distribution network, because of the resonant cavity structure formed by the power supply / ground plane, when the return current passes through the power / ground plane, the signal frequency is close to or reaches the inherent resonant frequency of the board. Resonance between the power supply and ground plane results in the maximum input impedance Zpp. As a result, the signal can not be transmitted between the boards, and the return path of the current is hindered, which will radiate from the (PCB) edge of the multilayer printed circuit board in the form of electromagnetic waves. Another is the radiation problem caused by noise introduced into the power / ground plane. In order to control the noise radiation of the power / ground plane, this paper adopts the electromagnetic bandgap (EBG) structure, which is a hot research topic of noise suppression, that is, the method of dividing the power supply / ground plane. The high impedance surface of the electromagnetic band gap structure is used to suppress the formation of the surface current and to isolate the noise so as to reduce the radiation of PCB. Different from most papers, using EBG structure in the whole power / ground plane seriously destroys the power integrity of the board. The noise suppression effect is modeled by equivalent circuit model and the S parameter is calculated by HFSS. In this paper, partitioning units or EBG structures are arranged around the signal passing holes from a local point of view. The method of field analysis is used to analyze the segmentation units and EBG structures. The input impedance and radiation field strength are calculated by boundary element method, and compared with those of the PC-board without this kind of structure, which is composed of perforated cavity and power supply / ground plane structure, and the boundary element method is used to calculate the input impedance and radiation field strength of the resonator. The accuracy of the results is improved by using the field method. The boundary element rule only needs to discretize the boundary, does not need to solve the electric field value inside the region, and is suitable for any power / ground plane structure of any shape. Finally, the results are compared with the full wave simulation results of 3D electromagnetic simulation software ANSYS, and the effectiveness of the proposed method is verified. In view of the discontinuity of the current return path between the power supply and the ground plane, a reasonable return path for the current flowing through the power supply / flat panel is studied through the arrangement of SMT (sticker type) decoupling capacitors around the hole. The signal can be transmitted smoothly between plates, and the radiation of PCB board can be controlled. The field circuit method is used to model the resonant cavity structure which is composed of perforating, decoupling capacitance and power / ground plane, and the boundary element method is used to carry out the numerical calculation. This paper analyzes how to lay out decoupling capacitors, and calculates how much decoupling capacitors are arranged to make the decoupling effect better.
【學位授予單位】：集美大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN41
【參考文獻】
相關期刊論文 前1條
1 陳曦;梁昌洪;蘇子劍;梁樂;;一種新型的雙帶電磁帶隙結構[J];電波科學學報;2009年05期
，本文編號：2427053
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