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.     

矩形谐振腔串扰抑制方法研究

在高速数字系统中,信号完整性问题越来越突出,信号速率和设计密度的不断提高使得串扰上升为主要因素之一。先研究了基于矩形谐振腔的串扰抑制方法;然后与三倍线宽方法(3W方法)和有过孔接地的防护线方法的对比分析表明,矩形谐振腔方法对微带线间近端串扰的抑制能力不理想,但对远端串扰的抑制非常有效,在频域仿真中远端串扰幅度可提高12 dB和8 dB,在时域仿真中远端串扰峰值分别为前两种方法的18.2%和23.1%;最后进一步研究了矩形谐振腔的结构参数（间距、长度和宽度）对远端串扰的影响,发现这三个参数存在一组最优值,能最大程度地减小远端串扰。     

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。     

Early package analysis: considerations and case study

Several issues associated with multichip module (MCM) system design are discussed. An early analysis tool for evaluating the tradeoffs between a design and packaging technology is presented. A case study of a possible design point suggested by combining different package elements being used in MCMs settings is included. The case study indicates that the most effective packaging solution for high-performance applications, requiring multichip modules, will likely represent a progression from cofired ceramics (MCM-C) to a thin-film and hybrid cofired ceramic (MCM-D/C) module     

Quasi-TEM analysis of reciprocal/nonreciprocal planar lines with polygonal cross-section conductors

Multilayered multiconductor transmission lines with polygonal cross-section-perfect conductors are analyzed under a quasi-TEM approach. According to a model previously proposed by the authors, each polygonal cross-section conductor is modeled as a set of zero-thickness strips. The substrates can be lossy, and present possible gyromagnetic (longitudinal magnetization) characteristics as well as dielectric anisotropic properties. The method of moments of Galerkin is applied in the spectral domain to analyze the model structure. Special attention has been paid to the fast and accurate computation of spectral integrals. Thus, the possible symmetries of the Galerkin matrix are emphasized and recurrence formulas to compute the tail integrals have been developed. © 1994 John Wiley & Sons, Inc.     

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。     

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.     

基于时域积分方法分析PCB串扰问题

采用时域积分方程法及改进型节点分析法对PCB板间导线的串扰问题进行建模.时域积分方程法以等效原理为基础,在矩量法应用中加入时间因子的考虑,并采用RWG基函数将模型划分为多个三角面元,从而将导线间的影响以散射的角度来表达.另外采用改进节点分析法对电路边界不连续性进行求解,从而懈决了有限电导率导体和各向同性介质相结合情况下的串扰问题.最后在多层PCB传输线的算例中,计算给出了不同条件下输出电压和串扰电压波形的时域变化,从而对PCB板间信号完整性做出了分析.     

Isolation improvement in dual-band astroid shaped MIMO DRA for LTE and ISM applications

This article presents the design of a novel astroid shaped dielectric resonator antenna (DRA) constructed from PTFE Teflon material with a dielectric constant of ε_r = 2.1 and a loss tangent tan δ = 0.0002 on an FR4 grounded substrate for LTE and ISM band applications. Inverted Omega ?-shaped feed along with asymmetric E-shaped dual metallic strips in the partial ground is used to obtain dual-band characteristics. A light weight, cost-effective plastic material is used to design the antenna. An isolation of 26.5 dB and 24.6 dB is achieved in the two frequency bands 1.8 GHz and 2.4 GHz respectively by modifying the ground plane. Metallic strips and stubs in the ground are used to enhance the isolation in the proposed MIMO system. The obtained impedance bandwidths in both the bands are 14.5% and 13%. The performance of the MIMO system is characterized by the envelope correlation coefficient and diversity gain. Good agreement is found between simulated and measured results.     

Fabrication and characterization of PECVD silicon nitride for RF MEMS applications

The structural, optical and electrical properties of plasma enhanced chemical vapor deposited silicon nitride layers are investigated, which have been used as a dielectric layer during RF MEMS fabrication. During growth, the gas ratio (SiH₄/NH₃) is varied between 0.33 and 0.5 and pressure is varied between 400 and 700 mTorr while deposition time is kept constant. The results in the films show differing properties. The thicknesses of the resultant films are between 150 to 220 nm with different gas flow ratios and pressures whereas the deposition time was kept constant. A Bruggeman effective medium approximation is utilized to model the refractive index of the films. Reflectance measurements were carried out in the range of 210–250 nm. The refractive indexes of the films varied between 1.79 and 2.03, with a dielectric constant varying from 6.66 to 7.22. Capacitance voltage measurements yield a fixed dielectric charge value in the low ?10¹² cm^?2 while a breakdown voltage of 915 V μm^?1 is achieved for films grown at the lowest gas ratio and pressure. The quality of Si/Si_xN_y interface is also considered.     

高速应用的薄膜MCM材料评述

信号频率在１００ＭＨｚ以上时，材料性质对薄膜多芯片组件（ＭＣＭ－Ｄ）的性能变得越来越重要。本文讨论高频下材料性质对ＭＣＭ－Ｄ的电性能的影响。着重讨论介电常数、介质损耗角正切、互连金属电阻和互连金属趋肤深度等对系统性能的影响。对常用的ＭＣＭ－Ｄ材料的这些性质作了比较。     

基于传递函数的高速互连线串扰分析

针对互连线系统在高速信号激励下产生的串扰问题,导出高速互连线的时域分布参数系统模型,建立从激励电压到攻击线末端和受害线两端电压相应的传递函数,从系统的角度研究串扰噪声问题。仿真结果表明了该方法的有效性,与数值方法相比更具有一般性。     

Far‐end crosstalk reduction in PCB interconnects using stepped impedance elements and open‐circuited stubs

In this work, new trace configurations using stepped impedance elements and open‐circuited stubs to reduce far‐end crosstalk in printed circuit board (PCB) interconnects are introduced. The goal of this study is to reduce crosstalk without using additional PCB components in the design. Specifically, we use stepped impedance elements and open‐circuited stubs of uniform length and width on the victim traces to suppress high‐frequency electromagnetic interference and to equalize propagation delays or capacitive and inductive couplings between PCB traces. The overall design is very similar to the usual low‐pass filter configurations, which are difficult to implement in the prototype testing. The proposed approach shows remarkably better results when compared with conventional intervening guard trace schemes. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

Radiation characteristics of strip‐loaded dielectric‐coated conducting cylinder

The radiation characteristics of strip‐loaded dielectric‐coated conducting cylinder are investigated theoretically for the infinite and finite periodic structures. For the infinite case, the strip electric current expansion satisfying edge condition and the field expression with a summation of space harmonics are applied to solve a homogeneous matrix equation. The integral equation is derived for the finite structure by using the inverse Fourier transform and the strip current expansion. The influences of the strip width, cylinder radius, and finite strip number on the radiation characteristics (leakage constant, phase constant, radiation pattern, and beam scanning) are investigated. The results of the finite periodic strips are compared with those of the infinite extent structure and good agreement is found. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

An investigation on the effect of undercutting on the propagation parameters in single and coupled quasi-TEM lines in a multilayered dielectric

The effect of undercutting on the electrical parameters of general single and coupled quasi-TEM lines in a multilayered dielectric is studied by an efficient quasistatic numerical method. Results are presented for characteristic impedance, propagation constant, and attenuation constant in single lines; two symmetrical coupled lines; and a four-line system. In all cases studied a significant increase of losses has been observed.     

Conditions for line-based singularities in spatial platform manipulators

In this paper, we consider singular configurations of a robotic system that can be modeled as a platform supported by serial robotic chains. The goal is to determine the conditions under which these singular configurations depend purely on the geometry of lines associated with each supporting chain. These conditions are satisfied by many manipulator systems, particularly those based on the Stewart platform. A geometric classification of these “line-based” singularities is presented. © 1998 John Wiley & Sons, Inc. 15: 43–55, 1998     

气压扰动下介电弹性体球膜的随机响应分析

研究随机扰动的压力和恒常电压联合作用下的介电弹性体球膜,发展随机响应的分析方法并总结其规律,为计及介电弹性体的应变强化现象,其力学性能由Gent应变能模型描述,压力扰动近似为高斯白噪声.引入能量相关变换并应用随机平均法导出了关于系统总能量稳态概率密度的简化Fokker-Planck-Kolmogorov方程,并解析得到方程的解,从而得到球膜伸长比及其变化率的稳态概率密度,进而得到伸长比的各阶统计量.研究针对两种典型情形进行,即球膜在伸长比为1附近的振动及球膜在材料拉伸极限附近的振动.详细讨论了激励强度、材料参数及常电压值对伸长比统计量的影响,特别强调了不同的材料参数和常电压值引起的不同振动模式.蒙特卡洛模拟证实了分析结果的有效性和精度.     

Modelling crosstalk through common semiconductor layers in AMOLED displays

High pixel density displays are demanded for active matrix organic light‐emitting diode displays (AMOLED) in applications such as virtual reality headsets, micro‐displays, and high‐end smartphones. Parasitic emission from non‐addressed neighboring pixels (crosstalk) is a common problem in such high pixel density AMOLED, and this crosstalk becomes more severe as the pixel density and fill ratio of the display increases. One of the causes of crosstalk is parasitic currents that travel through common organic semiconductor layers. In this paper, we model and quantify the pixel crosstalk using a 2 + 1D finite element model that is based on the conductivity of the common layer and the luminance–current–voltage curves of the subpixels as measured input parameters. We assess the effect of crosstalk on the pixel current, observed color, and luminance. The 2 + 1D model limits the number of degrees of freedom so that calculations on a standard personal computer are feasible.     

High-performance MCM routing

The authors describe the multilayer MCM (multichip module) routing problem, and propose an approach for routing high-performance MCMs with the objective of minimizing interconnect delays and crosstalk. They first introduce an approach for rapidly estimating the time-domain response of lossy transmission line trees, and propose a realistic second-order delay model for MCM interconnects. The delay model is used to guide a performance-driven global routing algorithm. Given the 2-D global paths, the next stage is layer assignment. An effective algorithm for constrained layer assignment is developed. Based on the best-known maxcut approximation algorithm (which performs well in practice), a maximal k-color ordering is formulated for minimizing both interlayer and intralayer crosstalk as well as crossings in 3-D MCM substrates. The authors also propose a strategy that exhibits a good tradeoff between circuit performance and design cost, instead of concentrating exclusively on a single objective such as area minimization     

基于CAV424的油井含水率在线检测

不同含水率的油水混合物其介电常数差异也会很大,根据这一理论,本文设计了过流式的电容传感器,采用专用集成芯片CAV424将电容量转换成电压信号,并进行了高精度的AD采样,提高了测量的准确性。实验结果表明,该系统性能较好、测量精度高、成本低,具有较好的应用价值。