【作者】 李轶敏；

【导师】 顾长青；

【作者基本信息】 南京航空航天大学 ， 电磁场与微波技术， 2009， 硕士

【摘要】 信号完整性问题已成为高速数字电路设计中迫切需要解决的关键问题。随着高速数字电路工作频率的不断提高,信号上升/下降沿时间不断变短,电路集成度不断提高,延迟、反射、串扰、过冲、振荡和同步开关噪声等信号完整性问题日益突出。信号完整性问题的分析本质上是求解一个复杂的电磁场边值问题,为了精确分析这种复杂的电磁效应,采用基于电磁场理论的全波电磁分析方法求解复杂的电磁场边值问题是有效的。本文围绕电磁建模仿真这一主轴,从时域和频域对高速电路中一些典型结构进行信号完整性分析。本文所做的主要工作有:1.应用三维全波电磁仿真软件对高速互连中常见微带互连线以及常见不连续性的信号完整性性能进行分析;2.探讨走线间串扰随信号跳变时间、走线间距离、参考层高度等参数变化的规律;此外,在相邻走线间添加多点接地的隔离带以减小串扰,并对隔离带的尺寸以及过孔间距的选取进行了讨论,仿真显示良好接地的隔离带可以有效地降低信号线间的串扰;3.针对不完整参考面(非理想返回路径)情况下槽缝尺寸变化,数字/模拟地隔离对串扰的影响进行了分析并通过添加电容改善不完整参考面对串扰的影响;4.由于同步开关噪声(SSN)的存在,使得PCB电路存在着电磁干扰问题,本文分析了同步开关噪声的产生原因,采用不同电磁带隙结构(EBG)抑制SSN,提出采用多孔混合的EBG结构抑制SSN的方法,并通过仿真验证了用EBG抑制SSN方法的有效性。通过以上研究工作,论文得出的结论对高速电路的设计,解决信号完整性问题具有一定的指导意义。更多还原

【Abstract】 Signal integrity problems have become the most urgent problem in high speed digital system design. As the systematic clock frequency is growing higher, signal’s rise/fall time is getting shorter, and integrated degree of circuit continuously increase, signal integrity problems, such as delay, reflection, crosstalk, overshoot, oscillation and simultaneous switching noise, have become more and more critical in high speed digital circuit design.The signal integrity problems are electromagnetic (EM) problems in nature. In order to take complex electromagnetic effects into account, full-wave EM analysis based on EM theory must be resorted. Around the topic of EM modeling and simulation, high-speed interconnects have been analyzed for signal integrity issues in frequency and time domain.The main fruit of this dissertation on both theory and applications are listed as follows: 1.The micro-strip lines and various discontinuities are analyzed and their effects on signal integrity are discussed; 2.The crosstalk simulation model of two Parallel micro-strip lines is obtained. Using the model,some important parameters about crosstalk, such as signal rise/fall time, space width and height of image plane are studied. Ground trace between adjacent traces is proposed to suppress crosstalk. The width of ground trace and the distance between vias are discussed. Simulation results verify that using trace with multipoint grounding properly can reduce crosstalk effectively; 3.The effect of the imperfect reference planes on the crosstalk between interconnections are analyzed. Stitching capacitors crossing split reference planes supply a signal return path to deal with the crosstalk; 4. Because of simultaneous switching noise (SSN), there is electromagnetic interference (EMI) in PCBs. The main causes and the common methods to solve these problems are analyzed. Simulation results demonstrate the Electromagnetic Band-Gap (EBG) structures could achieve SSN suppression for even a wider and higher frequency range.The design guidelines for improved signal integrity are derived from the results obtained and the design of high speed circuits can be guided to solve signal integrity issues.更多还原