基于EBG微结构的高速数字系统EMI抑制技术及其机理研究

The simultaneous switching noise (SSN) and the electromagnetic noise caused by discontinuity of interconnection structures, etc. in the power distribution network (PDN) of high-speed digital system can introduce a lot of electromagnetic interference (EMI) issues such as power integrity (PI), crosstalk and radiated emission, which will significantly impact the reliability, stability, and electromagnetic compatibility of a system. With the fast development of digital system toward the direction of thinning, miniaturization and ultra-high speed, the frequency spectrum of noise electromagnetic wave becomes extremely wide, and the EMI problem gets ever more prominent and complicated. The present EMI suppression methods, such as embedded capacitance, absorbing materials, electromagnetic band gap (EBG), etc., have limited frequency band, bigger size, poor signal integrity, and other shortcomings, which result in they can't be widely applied. In this project, we intend to use the EBG microstructure method to suppress the EMI in high-speed digital system in a wide frequency range. The research contents include following aspects: the forbidden band characteristic and its mechanism of dielectric microstructure EBG formed by filling high DK material into the dielectric substrate; topology optimization of dielectric microstructure EBG; the performance and mechanism of composite dielectric microstructure EBG composed of high DK material and magnetic material. The research results will be of great importance for the research and development of high-performance high-speed digital system, as well as for satisfying the strict requirement of EMC performance.

高速数字系统电源分布网络（PDN）中的同步开关噪声和互连结构不连续性等产生的电磁噪声会引起电源完整性、串扰和辐射发射等电磁干扰（EMI）问题，严重影响到系统的可靠性、稳定性和电磁兼容性（EMC）。高速数字系统向轻薄化、微型化、超高速方向的快速发展使噪声频谱变得非常宽广，EMI问题变得愈加突出和复杂。目前的嵌入式电容、吸波材料、电磁带隙结构（EBG）等抑制EMI的方法存在频带受限、尺寸较大、信号完整性较差等不足，未能广泛应用。本项目拟通过介质型EBG微结构的方法实现对高速数字系统EMI的宽频带抑制。研究内容包括：介质基板添加高DK材料形成的介质微结构EBG的禁带特性与机理；介质微结构EBG拓扑结构的优化；高DK材料、磁性材料形成的复合介质微结构EBG的性能及机理。研究结果对高性能高速数字系统研发及满足严格的EMC要求具有重要意义。

本项目通过在高速多层印刷电路板电源/地平面的介质基板中嵌入高介电常数介质柱来抑制电磁干扰。研究了介质型EBG（电磁带隙）结构对噪声抑制的性能特点，分析了介质EBG结构参数对其禁带特性的影响。. 首先研究了噪声源周围均匀环形排列若干介质柱时对电磁干扰抑制的效果，并与噪声源周围布置实体连续高介电常数介质的性能进行了对比；然后研究了整个电源/地平面中嵌入二维介质EBG时的噪声抑制行为，分析了介质柱的介电常数、高度、间距等参数的影响，针对较厚基板介质嵌入薄膜介质柱的两种措施；研究了高效的数值建模分析方法；最后研究了渐变结构对介质EBG带宽的影响；此外简要阐明了磁性材料与EBG的关系及作用机理。. 研究结果表明：噪声源周围环形布置介质柱可形成一维介质EBG结构，可减少谐振，从而提高噪声抑制能力，但对相对厚的基板需采用很高介电常数的介质材料；采用高介电常数、薄膜型介质柱形成的二维介质EBG结构，可在宽频带内实现对电磁噪声的深度抑制；介质EBG的禁带宽度与介质柱的介电常数、间距密切相关，而介质柱和基板介质的高度与介质EBG的噪声抑制深度有关；渐变形EBG对扩展高频禁带宽度有显著作用，但由于容性下降带外抑制性能有下降；本项目所提区域分解法提供了一种适用于微结构复杂边值问题的高效数值建模方法；此外，本项目所提出的较厚的基板介质中埋入薄膜介质EBG的措施具有感性、容性EBG互调的优异特性。. 介质型电磁带隙结构同时具有EBG属性和容性属性，不仅可有效抑制噪声，同时对信号完整性、电源完整性、辐射发射等性能均得到改善。研究成果可推广到集成电路、柔性电路、射频电缆等领域，具有广阔的应用前景。