高速芯片封装中多平行传输线的设计与优化

随着封装基板朝着高阶高密度方向发展,其信号完整性问题也日趋严重。为研究高速互连结构中反射、串扰等问题与封装基板类型、设计参数和传输线物理特性的相关性,改进了简单的二线平行耦合模型,采用三维电磁仿真软件构建了新的封装级三平行传输线模型,分析了陶瓷基板与有机基板上的传输线反射和串扰特性,研究了该结构下减小反射系数与串扰噪声的方法。仿真结果表明,封装基板上传输线反射系数S11与阻抗匹配程度相关,受信号线宽、厚度和介质厚度影响较大,且S11最小值在不同频率下匹配的最优线宽也不同,需根据不同信号频率具体选择。近端串扰系数受边缘场作用,与线间距密切相关,远端串扰系数受介质厚度影响较大,在相同条件下,远端串扰噪声一般小于近端串扰,对其评估时需结合基板上信号密度、基板材料特性和介质厚度具体分析。     

一种基于反相器减小传感器信号线间串扰方法

传感器信号传输时由于信号线间的电磁耦合产生不可避免的串扰。信号线间串扰严重影响信号线系统信号完整性。针对传感器信号线间串扰提出一种抑制方法,基于反相器防护线减小信号线间串扰方法,该防护线物理结构非常简单,从而很好地减小物理设计成本。通过PSpice软件搭建仿真电路进行仿真验证,仿真结果表明：未采用反相器防护线的受害线受到串扰严重且信号发生误码现象,而采用反相器防护线后受害线串扰现象明显改善且传输信号和原始传输信号100%吻合,从而验证了反相器防护线具有很强的抑制传感器信号线间串扰能力。     

多用户VDSL2系统远端串扰抵消算法

随着宽带接入网速率提升,VDSL2技术成为最后一公里的主流接入方式。用户数量急剧增加使传输线路之间串扰成为制约VDSL2系统性能的重要因素,线路之间串扰分为近端串扰（NEXT）和远端串扰（FEXT）,VDSL2系统采用正交频分复用调制技术,近端串扰可以通过滤波器滤除,远端串扰却无法消除。主要研究VDSL2系统远端串扰噪声消除的方法,提出远端串扰噪声如何进行评估和计算,推导出远端串扰噪声计算公式,通过公式可以计算出每条线路受到其他线路串扰噪声的大小,然后发送信号时通过串扰噪声预抵消运算,接收到的信号就能成功消除串扰噪声的影响,提高了接收信号的SNR值,进而提升了VDSL2传输速率。     

高速互连总线结构中多平行传输线间的串扰分析与控制

随着数字芯片和系统的时钟频率不断提高, 串扰成为高速互连系统设计、分析中不容忽视的严峻问题。为研究串行总线结构中多平行传输线间串扰的影响, 分析了电信号传输时串扰产生的机理, 采用信号完整性分析软件Hyperlynx, 构建了三平行传输线串扰模型和总线电路模型, 研究了不同模型中控制多平行传输线间串扰噪声的方法。仿真验证结果表明, 增加传输线间距、减小介质层厚度、进行端接匹配可以明显减小平行传输线间的串扰。最后提出了减小总线电路模型中抑制串扰噪声干扰的相应措施。     

基于时域特征的角位移传感器信号线间串扰方法研究

传统串扰方法计算得到的数据时域特征较弱,难以应用到不同的信号线间串扰问题分析中,为此提出基于时域特征的角位移传感器信号线间串扰方法.根据串扰基本原理,提取角位移传感器参数特性,通过相敏检波计算信号频率差异值,得到角位移传感器信号的时域特征,构建基于时域特征的串扰模型.设置单线、绞线以及屏蔽线三组不同的信号线,利用本文提出的方法和传统方法获取串扰数据.实验结果表明,两组方法可以获得角位移传感器与单线间的串扰;当端接电阻值增大到100Ω时,本文方法能够获得角位移传感器与绞线间的串扰;当测试角位移传感器与屏蔽线间的串扰时,本文方法可以获得具有对称性质的近端与远端串扰波形.     

微带线间远端串扰的电磁仿真研究

为研究降低远端串扰的方法,利用Ansoft HFSS软件对线间串扰进行电磁仿真研究.研究表明,通过添加防护线、覆盖介质层等措施可以降低远端串扰的影响.在一定频率范围内增加RSR结构中金属贴片的长度和数量,使金属贴片厚度接近微带线厚度等措施,会具有更好的效果;选择具有较高相对介电常数的覆盖介质层材料及增大介质层的厚度也可以降低远端串扰的影响.     

基于隔离带方法的两平行微带线间串扰抑制分析

在实际工程中,由于PCB的物理尺寸逐渐趋向于小型化,系统布线趋向于密集化,设计人员很难对强信号线的干扰按照传统的串扰抑制准则进行设计;在此背景下,文章采用在强信号线两边各加一排顶端用迹线连接的接地孔(简称隔离带)的方法来对其进行屏蔽,以减少微带线间串扰;在模型建立过程中添加了微带线高度及接地平面厚度两个参数,完善了采用隔离带方法来抑制线间串扰的仿真模型,并通过Ansoft公司的HFSS软件验证了此方法是有效的;在隔离带参数设置上,仿真结果表明,通过改变相关隔离带参数S1、g、d、h可进一步抑制线间串扰。     

PCB传输线间串扰抑制方法分析

研究数字电子技术设备中,串扰是印刷电路板(PCB)上电磁兼容的重要内容之一.为了抑制PCB传输线间串扰,提高系统信号准确性,消除噪音,通常在传输线间插入一列用金属填充的、顶端用微带连接的接地柱线(简称保护带).由于加有保护带的传输线系统结构复杂,理论分析比较困难,利用网络级联的方法对加有保护带的传输线建模进行分析.计算分析结果表明,加入保护带能有效地抑制线间串扰,保护带参数(接地柱间距、半径)的变化对串扰抑制有明显影响.研究对工程中正确设置保护带以降低串扰提供了必要的参考.     

微带线间远端串扰下电路板故障信号检测

在高精度电路板上,电路上的微带信号线路相邻很近.在工作中,由于线路过于接近,形成较强的微带线间远端串扰.这种串扰对电路本身的故障信号的波形造成感染,使得故障信号形成非正常的信号衰减形变.传统的电路故障检测方法在微带线间远端串扰的影响下,对衰减信号提取出现较为明显的失真,为后期的故障信号判断带来难度,降低了故障检测的准确率.提出一种关联信号特征提取的微带线间远端串扰下电路板故障信号检测的优化算法.利用小波变换对微带线感染信号进行滤波,利用卡尔曼算法对故障信号的主成分进行提取,运用主成分的差异特征完成了电路板的故障信号检测.实验结果表明,利用优化算法进行微带线间远端串扰下的电路板故障信号检测,能够极大的提高对故障信号检测的准确性.     

基于HyperLynx的电视跟踪系统信号完整性分析

在HyperLynx环境下,对反射和串扰这两种常见的信号完整性问题进行了仿真分析,提出了反射和串扰的抑制方案以及差分线的布线策略,在此基础上对以TS201为核心的电视跟踪系统的设计进行了改进。测试结果表明,在系统设计中进行有效的端接和合理的布局布线,可以提高信号的传输质量,避免和减小信号完整性问题。     

A novel method for crosstalk reduction in coupled pair microstrip lines

This article demonstrates novel ideas for mitigation of far‐end as well as near‐end crosstalk in coupled pair microstrip lines (CPMLs) by means of defected microstrip structure (DMS). Simple equations and models for analysis and design of a DMS are presented and extracted. Different configurations of DMS‐CPMLs are introduced, and their performances in crosstalk reduction are compared. Finally, the best configuration for far‐end crosstalk reduction is fabricated and tested. A maximum of 35 dB reduction in far‐end and 38 dB reduction in near‐end crosstalk are achieved. The signal integrity performance of the structure is also verified by eye‐diagrams. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2012.     

Crosstalk analysis of multi‐microstrip coupled lines using transmission line modeling

This article presents a new analytical method to predict crosstalk of a homogeneous terminated two microstrip coupled lines over a ground plane using transmission line theory. The derived formula is frequency and location dependent, which can be used to quickly estimate the crosstalk of a coupled line. Also, the effect of the geometrical parameters of the lines and load are included in the derived formula. Presented method can be used for the other types of coupled lines including lossy or lossless lines. To verify the accuracy of the introduced method, a few microstrip coupled line structures with different geometrical parameters are considered numerically and experimentally. The results of crosstalk based on the proposed analytical methods, simulation study using high frequency structure simulator and those obtained by measurements are reported and compared with each other. It is shown that our proposed method accurately estimates the amount of crosstalk for a two microstrip coupled lines.     

Microstrip dual‐band bandpass filters using parallel‐connected open‐loop ring resonators

This article proposes a microstrip dual‐band bandpass filter that uses parallel‐connected open‐loop ring resonators. Compared to many microstrip dual‐band filters, the advantages of using microstrip open‐loop ring resonators are easy calculation (half‐guided‐wavelength), easy fabrication (equal width for all 50‐Ω lines and without grounding holes), and direct connection to external feed lines (reducing insertion loss caused by gap couplings). Another advantage of the filter is an asymmetrical feed on the ring resonator that provides sharp rejections at its adjacent bands. The input and output matches of resonators to the external feed lines are derived using a simple transmission‐line theory. The results of the derivation provide a simple design rule for filter designers. Simulated and measured results are presented with good agreement. The filter has minimum insertion loss of 1.25 dB at 1.85 GHz and 1.6 dB at 2.33 GHz. The 3‐dB fractional bandwidths are 5.9% for the 1.9‐GHz bandpass filter and 4.7% for the 2.4‐GHz bandpass filter, respectively. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

Crosstalk analysis of uniform and nonuniform lossy microstrip‐coupled transmission lines

In this article, an analytical method is presented to precisely estimate the crosstalk of uniform and nonuniform microstrip‐coupled transmission lines (TLs) in frequency domain using modified transmission matrix. The obtained expression is quantitatively related in terms of the geometrical parameters of the coupled lines. A straightforward procedure is presented to obtain a closed form formula to accurately determine the crosstalk of a microstrip‐coupled line. For a nonuniform structure, the TL is divided into a few series of uniform sections with a specific modified transmission matrix. The total modified transmission matrix is determined by multiplying the modified transmission matrix of different sections and then the crosstalk can be calculated using the total modified transmission matrix. Several structures are considered to confirm the validity of the presented method. It is shown that the obtained results are in a good agreement with those obtained by simulation and measurement.     

An efficient method for analyzing nonuniformly coupled microstrip lines

This article presents an efficient method for analyzing nonuniformly coupled microstrip lines. By choosing a modal‐transformation matrix, the coupled nonlinear differential equations describing the symmetric nonuniformly coupled microstrip lines are decoupled using even‐ and odd‐mode parameters; the original problem is thus transformed into two single nonuniform transmission lines. A power‐law function of arbitrary order and having two adjustable parameters is chosen to better approximate the equation coefficients. Closed‐form ABCD matrix solutions are obtained and used to calculate the S‐parameters of nonuniformly coupled microstrip lines. Numerical results for two examples are compared with those from a full‐wave commercial package and experimental ones in the literature in order to demonstrate the accuracy and efficiency of this method. This highly efficient method is employed to optimize a cosine‐shape 10‐dB codirectional coupler, which has good return loss and high directivity performance over a wide frequency range. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005.     

Wideband and wide stopband superconducting bandpass filter using asymmetric stepped‐impedance resonators connected to open stub

A wideband wide stopband filter is designed using asymmetric stepped‐impedance resonators (ASIRs) connected to a large open stub. The capacitive open stub and the parallel‐coupled microstrip line are used to achieve the strong couplings for large fractional bandwidth (FBW). For a wide‐stopband performance, the proposed filter uses ASIRs to improve the high‐order spurious resonant frequency. The first and last resonators of the proposed filter are further optimized to suppress the spurious resonant frequency caused by open stub. The final filter has a 70% FBW centered at 4.87 GHz with 20‐dB‐rejection stopband up to 15.78 GHz (approximately 3.24 f₀). The measured insertion loss is less than 0.15 dB and the return loss is better than 17 dB.     

基于枝节加载多模谐振器的电调微波滤波器设计

针对认知无线电技术对射频微波滤波器的新要求,提出了一种基于枝节加载多模谐振器的电调微波滤波器。该电调微波滤波器由一个枝节加载微带多模谐振器和变容二极管组成,实现了滤波器的小型化。在分析枝节加载微带多模谐振器的基础上,通过在微带谐振器两端和加载枝节上加载变容二极管的方法,设计了枝节加载的电调多模微带谐振器,并提出了复杂微带谐振器谐振特性的分析方法。采用源和负载耦合的方法在通带右边引入一传输零点。通过在源和负载端放置耦合线的方法,提高了滤波器的通带选择性。针对滤波器带外衰减小的问题,引入一种新型的频变馈电结构,改善了滤波器的带外衰减特性。通过优化仿真确定了电调滤波器的尺寸参数。仿真验证了该滤波器的特性,当变容二极管的可调范围为2pf-10pf时,滤波器的频率可调范围为2.10GHz-2.40GHz,频率变化范围为300MHz。     

Frequency response of in-plane coupled resonators for investigating the acceleration sensitivity of MEMS tuning fork gyroscopes

The frequency response of in-plane coupled resonators is used for investigating the acceleration sensitivity of a MEMS tuning fork gyroscope (TFG) and a new method of suppressing the acceleration output is presented. The unbalancing of two sense resonators in the TFG caused by fabrication errors converted an external vibration into anti-phase mode excitation. To reduce the acceleration output, decoupling between in- and anti-phase modal frequencies [decoupling ratio (DR)] is crucial, since coupled resonators may cause large anti-phase vibrations from the acceleration. The acceleration output model was verified using two coupled resonators with 1 and 5?% stiffness unbalance. FEM simulation results showed a 25?% reduction in the anti-phase vibration by increasing the decoupling ratio from 0.09 to 0.29, irrespective of the coupled resonators designs. Quantitative analysis of a TFG based on coupled resonators with 1?% stiffness unbalance showed the acceleration output decreased from 5.65 to 1.43?deg/s/g.