耦合传输线信道传输矩阵建模及串扰抵消效果分析

针对高速互连系统中传输线上的串扰问题,基于电磁耦合理论,研究了耦合传输线信道传输矩阵的性质,建立了以下两种情况的耦合传输线信道传输矩阵模型及其矩阵分解形式,分别是：（1）考虑受扰线两边各一条相邻微带线对受扰线的串扰;（2）考虑受扰线两边各两条相邻微带线对受扰线的串扰.给出了上述两种情况下基于耦合传输线信道传输矩阵分解形式的串扰抵消方案,并利用仿真工具ADS对其进行了验证.结果表明：信号抖动和失真大幅下降,串扰抵消效果良好,并且第二种情况下的串扰抵消效果优于第一种情况.该结果说明了在基于耦合传输线信道传输矩阵进行串扰抵消时,考虑两边各两条相邻微带线的串扰效果较好,对保持高速信号完整性具有一定的实际应用价值.     

基于串扰与干扰源相位同步的减小串扰研究

基于串扰信号相位改变与干扰源信号相位改变具有同步的特性,提出了一种在干扰线中点利用信号反相来减小串扰的方法。n条总线系统中,在编号为奇数(或者偶数)的传输线中点插入反相器,使每条传输线在前二分之一耦合长度和后二分之一耦合长度上获得的远端串扰信号幅度相等、相位相反,前后两部分耦合长度所产生的串扰信号经过自动叠加后,传输线上的远端串扰就会被抵消。仿真结果表明:所提出的方法能够明显抵消串扰。     

屏蔽腔体中多导体传输线串扰抑制的仿真研究

屏蔽腔体中的传输线串扰是典型的电磁干扰问题,消除或减少串扰是非常必要的。在此建立了腔体内多导体传输线的串扰模型,采用电磁仿真软件研究抑制传输线间串扰的方法,分析受扰线终端接有滤波器前后的串扰电压时频响应特性。仿真结果表明,传输线终端接上相应频带的滤波器,可以滤除传输线上除工作信号以外的干扰信号,为电子系统线缆电磁防护设计提供参考依据。     

基于Hyperlynx的变电站状态监测无线节点信号完整性仿真分析

在变电站状态监测系统无线节点PCB设计过程中,由于存在高速电路,所以不可避免的会遇到信号完整信问题.借助IBIS模型和HyperLynx仿真软件对无线节点中的关键信号进行了反射和串扰的仿真研究.在未进行任何抑制措施时,反射和串扰对信号的影响较大,上冲和下冲幅值远大于200 mV,串扰幅值最大为370 mV.通过串联端接和加大传输线间距、减小耦合长度,反射和串扰对信号的影响明显减小,满足了信号完整性要求.     

基于传输线方程的多根非平行传输线串扰分析

非平行结构的传输线在电力电子系统中普遍存在,当其上通有电压和电流信号时,会在周围传输线上产生串扰响应。采用时域传输线方程建立多根非平行传输线之间的串扰模型,结合FDTD方法,分析在脉冲集总源激励下受扰导线始端和终端负载上的串扰电压响应特性,将其结果与仿真结果对比,验证了该方法的正确性。研究结果表明,非平行结构中受扰线始端和终端负载上的串扰电压响应随着传输线离地面高度的增大而增大,随着传输线之间夹角的增大而变小,且减小的趋势逐渐减弱,从而为线缆间的串扰防护提供了参考依据。     

平行传输线间串扰的仿真及分析

在高速电路设计中,信号完整性问题越来越突出,已经成为高速电路设计师不可避免的问题。该文重点研究了平行传输线间的串扰问题,通过信号完整性分析软件Hyperlynx建立了三线串扰模型并进行仿真分析,最后提出高速PCB设计中减小串扰噪声的策略。     

高速数字电路PCB中串扰问题的研究与仿真

针对高速数字电路PCB中传输线间串扰的严重性,从精确分析PCB中串扰噪声的角度出发,在传统的双线耦合模型的基础上,采用了一种三线串扰耦合模型。该模型由两条攻击线和一条受害线组成,两条攻击线位于受害线的两侧,线间采取平行耦合的方式。利用信号完整性仿真软件Hyperlynx对受害线上的近端串扰噪声和远端串扰噪声进行了仿真。仿真结果表明,不同的传输模式和传输线类型、信号层与地平面的距离、耦合长度、传输线间距和信号上升/下降沿等因素会对受害线上的近端串扰和远端串扰产生较大的影响。在分析仿真结果的基础上,总结出了高速PCB设计中抑制串扰的有效措施,对高速数字电路设计有一定的指导意义。     

基于高频高速PCB应用的新型差分线结构

本文通过分析高频高速PCB上串扰产生的机理,以两条传输线之间的耦合电容和耦合电感等作为优化的参量,提出了一种改善信号串扰的差分线结构———T型差分传输线,采用正交实验方法研究 T型差分传输线结构的多个参数对远端串扰的影响,得出了改善信号远端串扰的最优组合方案,确定了这些参数对改善串扰的重要程度及主次顺序,利用HFSS对T型差分传输线和Tabbed Line进行仿真对比分析,仿真结果表明 T型差分传输线改善串扰的效果明显优于Tabbed Line。     

一种有效的系统芯片串扰故障激励检测模型

目前的系统芯片(SOC)制造技术已经进入了深亚微米时代,由于系统芯片内部信号传输线发生串扰而导致系统功能失效的串扰故障问题不容忽视。文中在对系统芯片中信号传输线的串扰产生性质进行深入研究的基础上,提出一种简单有效的系统芯片串扰故障激励检测模型——基于搜索的MAF模型。对使用这种串扰故障激励模型的效率和已有的MAF模型进行了对比。结果显示在串扰较弱时,其所需的检测矢量数和已有的MAF模型相当;而在串扰较严重时,这种新的串扰故障激励检测模型只需较少的激励检测矢量即可以完成对所有串扰故障的激励检测。     

IC高密度陶瓷外壳串扰对信号完整性的影响

在高密度陶瓷封装外壳设计中,遇到的包括单信号线的延迟、反射和多信号线间的串扰等噪声问题,以及电源完整性问题,这些问题都严重影响整个电子系统性能的信号完整性。基于高速电路传输线的信号完整性相关基本理论,通过测试和仿真的方法来研究传输线间近端串扰和远端串扰问题。对大规模集成电路外壳CQFP240M进行串扰测试分析,利用仿真软件CST建立微带线和带状线模型,仿真、测试分析相邻传输线间串扰大小的影响因素。根据仿真结果,提出降低串扰的方法,优化设计,提高传输结构性能。     

Cross‐talk Cancellation Algorithm for 3D Sound Reproduction

If the right and left signals of a binaural sound recording are reproduced through loudspeakers instead of a headphone, they are inevitably mixed during their transmission to the ears of the listener. This degrades the desired realism in the sound reproduction system, which is commonly called ‘cross‐talk.’ A ‘cross‐talk canceler’ that filters binaural signals before they are sent to the sound sources is needed to prevent cross‐talk. A cross‐talk canceler equalizes the resulting sound around the listener's ears as if the original binaural signal sound is reproduced next to the ears of listener. A cross‐talk canceler is also a solution to the problem—how binaural sound is distributed to more than 2 channels that drive sound sources. This paper presents an effective way of building a cross‐talk canceler in which geometric information, including locations of the listener and multiple loudspeakers, is divided into angular information and distance information. The presented method makes a database in an off‐line way using an adaptive filtering technique and Head Related Transfer Functions. Though the database is mainly concerned about the situation where loudspeakers are located on a standard radius from the listener, it can be used for general radius cases after a distance compensation process, which requires a small amount of computation. Issues related to inverting a system to build a cross‐talk canceler are discussed and numerical results explaining the preferred configuration of a sound reproduction system for stereo loudspeakers are presented.     

存储阵列中的串扰分析及脉冲产生电路设计

在SRAM存储阵列的设计中,经常会遇到相邻信号线与电路节点间耦合引起的串扰问题。针对这个问题给出位线“间隔译码”的组织结构,有效地降低了存储器读写时寄生RC所带来的串扰。同时,针对该“间隔译码”的存储阵列结构,设计了脉冲产生电路,该电路只需要利用行地址的变化来生成充电脉冲,不仅简化了电路的规模,而且减小了读写操作时存储阵列中单元之间的串扰,提高了可靠性。     

Digital signal processing techniques in Nyquist-WDM transmission systems

In single-carrier wavelength-division multiplexing (WDM) systems, the spectral efficiency can be increased by reducing the channel spacing through digital signal processing (DSP). Two major issues with using tight filtering are cross talk between channels and inter-symbol interference (ISI) within a channel. By fulfilling the Nyquist criterion, Nyquist spectral-shaped WDM systems can achieve narrow channel spacings close to the symbol rate \((\hbox {R}_{\mathrm{S}})\) with negligible cross talk and ISI. In principle, DSP can generate any signals with arbitrary waveforms and spectrum shapes. However, the complexity of DSP is limited by its cost and power consumption. It is necessary to optimize the DSP to achieve the required performance at a minimum complexity. In this paper, we first introduced the background of digital signal processing for Nyquist spectral shaping in optical fiber WDM systems. Then, we investigated the use of digital finite impulse response (FIR) filters to generate Nyquist-WDM 16-ary quadrature amplitude modulation (16QAM) signals with the raised-cosine (RC) and root-raised-cosine (RRC) shape spectra. The system performance of both the RC and RRC spectra is also examined. Moreover, we explored the various methods to reduce digital-to-analog converter (DAC) sampling speed, such as using super-Gaussian electrical filters (E-filter) and spectral pre-emphasis. We also discussed receiver-side matched filter design for Nyquist-WDM receiver optimization.     

Modeling and measurement of cross‐talk transmission between coupled lines

In multiwire cables, high‐frequency signals can, and do, propagate not only by direct conduction over a pair of wires the signal was inserted to but also by electromagnetic coupling between adjacent transmission lines formed out of multiple wire pairs, too. Thus, it is useful to be able to measure relevant parameters, dependent of cable geometry and isolation material, that would enable modeling of cross‐talk propagation. In this article, signal propagation between ports of two coupled lines is first theoretically analyzed using z‐parameters. Then, the physical quantities needed for calculation of z‐parameters in systems with electrically long cable sections were defined and measured, and the results were verified against measurements performed on real cables. Copyright © 2014 John Wiley & Sons, Ltd.     

Comparative investigations of DWDM transmission system with PMD for different orthogonally modulated signals at 80 Gb/s

Polarization mode dispersion (PMD) has become one of the major limiting factors for high‐bit‐rate optical transmission systems. This paper evaluates the performance of dense wavelength division multiplexed (DWDM) system with PMD at 80 Gb/s in the presence of Kerr‐nonlinear effects. Orthogonally modulated signals have been investigated and compared for tolerance against PMD in a DWDM transmission system with direct detection receivers. The optimized combinations of orthogonal polarization (OP) with carrier‐suppressed return‐to‐zero (CSRZ) and CSRZ differential‐phase‐shift‐keying signals are shown to improve PMD tolerance over high bit rates and long transmission lengths. Improved performance greater than 4 dB is observed for CSRZ modulated signal with OP because of less channel cross talk and reduced power transfer between adjacent bits over different PMD values. The numerical results demonstrate that our proposed orthogonally modulated signals perform better with lesser complex direct detection receivers. Copyright © 2015 John Wiley & Sons, Ltd.     

基于有限元分析的推力矢量测试平台研究

重点介绍了一种压电石英式推力矢量测试平台。用有限元分析工具对测力平台模型进行静力学分析,并对测力平台的关键尺寸进行结构参数优化设计,以达到减少非线性和横向干扰的目的。实验结果表明:该测力平台具有良好的静态性能指标,灵敏度、线性度都达到了设计要求,直接输出的相间干扰在2%以内,可以满足推力矢量测量的需要。     

Crossing the planes at high speed. Signal integrity issues at splitground and power planes

This article discusses a specific design situation that represents quite a broad class of problems in the study of signal integrity. The article focuses on the effects on high-speed signals that need to cross split ground planes and split power planes that act as signal references or partial references. Such configurations are frequently needed in the layout of printed circuit boards (PCBs), multichip modules (MCMs), and even single-chip modules. Examples of split ground and power planes are discussed first. The conventional effective inductance model is described briefly, and an accurate and efficient transmission line model is then discussed in detail. Examples of modeling and design trade-offs are also presented     

Analysis of Miniature Electric Field Probes with Resistive Transmission Lines

The miniature dipole probe is a useful tool for measuring the electric field at high radio and microwave frequencies. A common design for the probe consists of an electrically short dipole antenna with a diode across its terminals; a resistive, parallel-wire transmission line transmits the detected signal from the diode to the monitoring instrumentation. The high resistance per unit length of the transmission line reduces the direct reception of the incident field by the line and also reduces the scattering of the incident field by the line. In addition, the resistive transmission line serves as a low-pass filter in the detection process. In this paper, the effect of the resistive transmission line on the operation of the miniature field probe is analyzed. Specifically, the reception of the incident signal by the transmission line is compared with that of the dipole. The scattering of the incident signal by the transmission line is studied by means of the scattering cross section, and the limitation imposed on the measurement of amplitude-modulated signals by the low-pass filtering by the resistive line is examined. The results of the theoretical analyses are presented as simple formulas which are useful in the design and optimization of the probe. The theoretical results are shown to be in good agreement with measurements.     

交叉相位调制对密集波分复用系统性能的影响

研究了交叉相位调制对密集波分复用系统性能的影响 ,分析了干扰信道为正弦调制时交叉相位调制效应对考察信道相位的影响 ,在此基础上 ,建立任意信号通过具有交叉相位调制效应的信道时的系统模型 ,并将该模型应用于基带不归零码数字信号传输的情形 ,计算了由交叉相位调制引起的系统光功率代价。结果表明 ,交叉相位调制效应对高速率调制系统的性能具有一定的影响 ,应该在系统设计时的功率预算中予以考虑。