The Cyclostationary Nature of Crosstalk Interference from Digital Signals in Multipair Cable--Part I: Fundamentals

This paper considers the cyclostationary nature of digital signals when determining crosstalk interference between such signals in multipair cable. This approach is necessary as the interference is only relevant at the decision instants in the receivers of the disturbed systems and any time variation of this interference with respect to the sampling instants changes the effect of this interference; previous studies in the area have ignored the cyclostationary nature of the digital signal. Expressions for the time-varying mean and variance of far-end and near-end crosstalk (FEXT and NEXT) have been derived. These expressions demonstrate the inherently smaller time variation of the NEXT interference when compared to the FEXT interference. An interesting result is that the calculation of the time-averaged value of the variance of FEXT and NEXT interference still requires the use of the cyclostationary properties of the digital signal. The results of this paper are extended and applied to various examples of the engineering of digital line systems in multipair cable in Part II of this paper.     

Error probability due to Gaussian noise and near-end crosstalk

The error probability is calculated of a baseband digital system operating on multipair cable subject to Gaussian noise and near-end crosstalk from a number of interfering plesiochronous digital systems carrying a.m.i.-coded random binary signals.     

Design Criteria for Crosstalk Interference Between Digital Signals in Multipair Cable

This paper proposes design criteria for the crosstalk interference between digital line systems operating in multipair cable, with plesiochronous and synchronous network configurations. Existing solutions are shown to be appropriate in some cases, in some other cases to be based on imperfect design criteria, and in other cases, such as the plesiochronous case, to be absent. For engineering purposes, the application of a 3 dB additional margin to the design criterion based on the classical solution should be adequate for practical application in the network.     

微米级平行互连线的测试结构设计

研究分析无串扰传输理想模型的条件,根据高速高密度电路板中微米级、亚毫米级互连线电磁串扰特性研究需要,首次提出微米级平行互连线的测试结构设计。经射频电路理论分析推导了测试结构对系统串扰没有影响。构建了有、无测试结构的微米级平行互连线物理模型,仿真分析后,加工制作有测试结构的微米级平行互连线电路板。研究结果表明,当数字基带信号传输频率在0~3 GHz 范围时,无测试结构仿真电路模型、有测试结构仿真电路模型、有测试结构的实验电路板,三者串扰特性吻合;微米级平行互连线的测试结构设计合理,具有工程参 考价值。     

Binder MIMO Channels

This paper introduces a multiple-input multiple-output channel model for the characterization of a binder of telephone lines. This model is based on multiconductor transmission line theory, and uses parameters that can be obtained from electromagnetic theory or measured data. The model generates frequency-dependent channel/binder transfer function matrices as a function of cable type, geometric line-spacing and twist-length parameters, and source--load configurations. The model allows the extraction of the magnitude and the phase of individual near end crosstalk, far end crosstalk, split-pair, and phantom transfer functions from the transfer function matrix of the binder. These individual crosstalk transfer functions are often found to be very sensitive to small imperfections in the binder. Examples of category 3 twisted pair American telephone lines and ldquoquadrdquo telephone cables are also presented.     

NEXT and FEXT models for twisted-pair North American loop plant

Measurements of near-end crosstalk (NEXT) and far-end crosstalk (FEXT) in 26-AWG and 24-AWG polyethylene insulated cable (PIC) twisted pair cables are presented. This data is used to develop crosstalk models that indicate existing T1.417 Standard NEXT and FEXT models are probably conservative by about 5 dB for 25-pair binder groups. However, many cables start from wire centers as pulp cables of 100-pair binder groups. Even if most of these older pulp cables are 26-AWG, prudence dictates that a more conservative model be used for these cases. On a going forward basis for new and rehab construction, it should be recognized that PIC (air core and filled) cables with not larger than 25-pair binder groups are the predominant cable media supplied by manufacturers for feeder and distribution loops. Results for NEXT in 12-pair binders are also analyzed and show that 26-AWG cable has about 2 dB more NEXT loss than 24-AWG cable and 12-pair binders have about 2 dB more NEXT loss than 25-pair binders. In addition, the NEXT loss separation between adjacent binders of 12 and 13 pairs is found to be not more than 10 dB as compared with the more optimistic 15.5 dB assumed within the industry     

高密度封装中互连结构差分串扰建模与分析

针对传统模型存在较大分析误差的问题,提出高密度封装中互连结构差分串扰建模与分析。在对互连结构差分传输线耦合关系分析的基础上,建立了四线差分结构串扰模型。运用该模型对互连结构差分串扰中的电阻、电容以及电感进行等效分析,解决高密度封装中互连结构差分串扰问题。经试验证明,此次建立模型平均误差为0.042,满足抑制高密度封装中互连结构差分串扰问题的精度需求。     

An efficient crosstalk parameter extraction method for high-speedinterconnection lines

A proposal is presented for an effective extraction method for crosstalk model parameters of high-speed interconnection lines. In the extraction procedure, mutual capacitance and mutual inductance of the coupled interconnection lines are extracted based on S-parameter measurement, time-domain-reflectometry (TDR) measurement and subsequent microwave network analysis. The extraction method is useful for characterizing homogeneous guiding structures, where the propagation of coupled transverse electromagnetic (TEM) modes is supported. In contrast to previous extraction methods, the suggested procedure requires fewer on-wafer probing steps and does not need matched terminations in the test device for high-frequency probing. The extracted models can be readily used with simulation program with integrated circuit emphasis (SPICE) circuit simulation. The procedure can also be used for modeling the crosstalk in packaging structures and multichip modules (MCMs). The proposed procedure has been successfully applied to the crosstalk model extraction of on-chip interconnection lines. Crosstalk model parameters were obtained for different line structures, spaces, and widths. Finally, the validity and reliability of the extracted models were examined by comparing a SPICE circuit simulation using the extracted crosstalk model parameters with high-speed time-domain crosstalk measurement. A close agreement was observed in the amplitude and pulse shape between the simulation and the measurement, showing the accuracy and usefulness of the proposed extraction method     

Crosstalk on Cables: A Communication Theoretic Approach

The crosstalk induced in a particular cable by other nearby current carrying cables is of significance in predicting the behavior of systems using such cables. Unfortunately, computational difficulties and ignorance of the actual problem geometry (as opposed to the nominal geometry) often make the calculation of the crosstalk uncertain or impossible. In this paper a method is devised for expressing the rms value of the crosstalk, and the resulting expression is investigated for a particular class of cables. The models proposed are applicable only to long low-frequency cables constructed of nonmagnetic materials. Electrostatic effects are not considered.     

Microwave frequency crosstalk model of redistribution line patterns on wafer level package

As the operating frequency of systems increases above the gigahertz frequency range, the electrical performance of a package becomes more critical. Wafer level package (WLP) is a promising solution for future high-speed packaging needs. Because the length of the interconnection lines on the WLP is limited to die size, the WLP has a minimum number of electrical parasitic elements. Because the crosstalk generates significant unwanted noise in nearby lines, causing problems of skew, delay, logic faults, and radiated emission, the crosstalk phenomena is drawing more attention than ever among the electrical characteristics of the WLP. Consequently, the modeling of the crosstalk parameters of the WLP is very important when used in high-speed systems. In this paper, we first report the crosstalk model parameters of the WLP, especially for the redistribution layer. These can be easily embedded into SPICE circuit simulation. The model is represented by the distributed lumped circuit elements, such as the mutual capacitance and the mutual inductance. The crosstalk model was extracted from two-step on-wafer S-parameter measurements and was fitted to the measurements made at up to 5 GHz.     

深亚微米VLSI电路中互连线的几何优化设计

基于三维 L aplace方程的 Silvaco Interconnect3D模拟程序数值解 ,对互连寄生电容进行了计算 ,其结果用于 0 .2 5μm CMOS技术互连延迟及串扰的 SPICE模拟中。模拟结果表明 ,基于W/ P=0 .3～ 0 .4的布线准则可以获得最优的互连延迟与串扰 (Crosstalk)特性 ,通过优化互连线及驱动管的几何尺寸可以显著地减小互连线的延迟及串扰噪声。     

Clear as a bell [controlling crosstalk in uniform interconnections]

Designers are aware of several approaches to reduce crosstalk, such as the use of shields or differential links that require a particular structure for the interconnection. This article discusses known crosstalk mitigation methods and presents a different technique applicable in various situations, which provides a drastic reduction of crosstalk     

Prediction of Crosstalk in Ribbon Cables: Comparison of Model Predictions and Experimental Results

The prediction of crosstalk in ribbon cables is investigated. Experimental results are obtained for a 20-wire ribbon cable and compared to the predictions of the multiconductor transmission line (MTL) model. Based on the experimental configuration tested, it would appear that accurate predictions of crosstalk can be achieved in these controlled-characteristic cables. The prediction accuracies are typically within ±1 dB for frequencies such that the line is electrically short and ±6 dB for frequencies such that the line is electrically long. It was found that the parasitic wires in the cable can have a significant effect (as much as 40 dB) on the coupling between a generator circuit and a receptor circuit in the cable. Therefore, to achieve accurate predictions in ribbon cables, one must consider the interactions between all wires in the cable. The wire insulation evidently cannot be ignored for frequencies such that the line is electrically long. The impedance of the reference wire cannot be ignored for low frequencies where the common-impedance coupling dominates the electromagnetic-field coupling.     

Crosstalk Loss Requirements for PCM Transmission

We present in this paper a unified approach to the crosstalk interference problem arising in PCM transmission on paired cables. For bipolar signaling, and three types of commonly used channel shaping, viz., cosine, raised cosine, and Gaussian, we present the minimum average near-end crosstalk (NEXT) and far-end crosstalk (FEXT) loss requirements at any transmission rate as a function of repeater spacing and number of interfering pairs so as to meet a desired error rate objective. This will aid in indicating if new cables need to be developed for a proposed rate of transmission or, for a given cable, the error margin available for degradations other than crosstalk can be readily determined. Extension to other coding schemes is indicated, and crosstalk compatibility is examined for mixedTsystems, such asT1,T1C, andT2. Graphical results are presented to readily aid in system design of anyTcarrier with repeater spacings up to 70 dB.     

Modeling of interconnect capacitance, delay, and crosstalk in VLSI

Increasing complexity in VLSI circuits makes metal interconnection a significant factor affecting circuit performance. In this paper, we first develop new closed-form capacitance formulas for two major structures in VLSI, namely: (1) parallel lines on a plane and (2) wires between two planes, by considering the electrical flux to adjacent wires and to ground separately. We then further derive closed-form solutions for the delay and crosstalk noise. The capacitance models agree well with numerical solutions of three-dimensional (3-D) Poisson equation as well as measurement data. The delay and crosstalk models agree well with SPICE simulations     

一种线缆护套的屏蔽效能测试方法

设计了一种基于串扰理论的线缆护套屏蔽效能的测试方法,根据测试结果分析了屏蔽护套不同接地方式对线缆间感性耦合、容性耦合的影响,试验结果可为在实际工程中抑制线缆串扰提供依据。     

Application of the saddle point method for the evaluation of crosstalk implications in an arrayed-waveguide grating interconnection

The effect of in-band crosstalk can pose severe limitations in an optical network. In this paper, the implications of in-band crosstalk induced by an arrayed-waveguide grating (AWG) router in a passive N/spl times/N optical interconnection are analyzed with non-Gaussian statistics using a numerical model. The model is based on the saddle point approximation and takes into account fluctuations of the transfer function's sidelobes induced by the phase errors in the grating arms, phase noise, polarization variations, bit misalignment, and shot and thermal noise. The influence of these effects on the interconnection's bit error rate (BER) is analyzed. The validity of the Gaussian assumption for the crosstalk noise statistics is discussed. Finally, the model is used to examine the mean crosstalk requirements for various numbers of network nodes.     

Altered phase velocity lines for low crosstalk microstrip interconnection of high-speed digital circuits: design and experimental validation

Altered phase velocity lines are a novel kind of parallel microstrip lines for high-speed interconnection of digital circuits, on which the crosstalk is reduced by the different phase velocities of propagation on the adjacent lines. In this paper, a design method is proposed to optimize the geometry sizes of the altered phase velocity lines. The measured results of a prototype altered phase velocity pair designed by the proposed method are presented to validate the design method. And the effects of the process variation are simulated to analyze the robustness of the prototype in fabrication. The altered phase velocity lines outperform the symmetric parallel microstrip lines in terms of the lower far-end crosstalk (FrdCtk) and the lower dielectric loss. This technique reduces the FrdCtk in the pair of the microstrip transmission lines and does not significantly improve the near-end crosstalk. The prototype works at the speed of 2 Gbps for low crosstalk digital signal transmission, while it can transmit the high-speed clock signal at 10.5 GHz, so the altered phase velocity lines are a useful supplementary to the existing low crosstalk interconnection concepts in the scenario that the parallel microstrips have to be placed closely on printed circuit board.     

Expected Crosstalk Performance of Analog Multichannel Subscriber Carrier Systems

This paper determines the intelligible crosstalk performance of analog multichannel subscriber carrier systems. Using a 0.1 percent probability of intelligible crosstalk objective, the calculations determine that the equal level far-end crosstalk loss must exceed 55.6 dB. Based on crosstalk measurements of in-service cables in South Central Bell, it is shown that only a small fraction of the pairs fail the crosstalk objective. Hence, it is concluded that multichannel analog subscriber carrier systems can be applied without any cable crosstalk constraints.     

Screening efficiency of triaxial cables with optimum braidedshields

An investigation into the shielding effectiveness of triaxial cables employing wire shields with optimum braid constructions is described. Several triaxial configurations with different braid designs for inner and outer cables were simulated. It is shown that crosstalk performance of the triaxial cables are affected by both absolute values and polarities of the surface transfer impedances of the shields. The effect of electric field coupling on the overall crosstalk within the triaxial system has also been studied in both frequency and time domains. For triaxial cables with shorted braids, the effects of electric field coupling are limited to high frequencies, and their effects at low frequencies are small