Fast transient analysis of incident field coupling to multiconductor transmission lines

Due to the rapid surge in operating frequencies and complexity of modern electronic designs, accurate/fast electromagnetic compatibility/interference analysis is becoming mandatory. This paper presents a closed-form SPICE macromodel for fast transient analysis of lossy multiconductor transmission lines in the presence of incident electromagnetic fields. In the proposed algorithm, the equivalent sources due to incident field coupling have been formulated so as to take an advantage of the recently developed delay extraction based passive transmission line macromodels. Also, a method to incorporate frequency-dependent per-unit-length parameters is presented. The time-domain macromodel is in the form of ordinary differential equations and can be easily included in SPICE like simulators for transient analysis. The proposed algorithm while guaranteeing the stability of the simulation by employing passive transmission line macromodel, provides significant speed-up for the incident field coupling analysis of multiconductor transmission line networks, especially with large delay and low losses.     

A SPICE model for multiconductor transmission lines excited by anincident electromagnetic field

This paper describes a SPICE model that may be used for predicting the time-domain or frequency-domain voltages and currents induced at the terminations of a multiconductor transmission line (MTL) by an incident electromagnetic held. Explicit results for the entries in the SPICE circuit model are obtained for an incident uniform plane wave that may represent sources such as radio and television transmitters, radars, lightning, etc. The result relies on the transformation of the MTL equations into uncoupled modal lines by similarity transformations. The entries in the similarity transformations are provided for lossless lines. The model is implemented using controlled sources to implement the modal transformations and delay lines to implement the modal lines. If the model is implemented as a SPICE subcircuit model, the time-domain form of the incident field can be implemented as a source external to that subcircuit model so that changes in the line responses due to changes In the incident field waveform can be simulated without changing the subcircuit model. In order to avoid negative line delays, the result is restricted to incident waves having components of the propagation vector in the positive direction along the line. This restriction can be removed by simply reversing the line. The paramount advantages of the model are that both time-domain and frequency-domain results can be easily obtained with the existing SPICE code, and nonlinear loads, such as transistors and digital devices, as well as dynamic loads, such as inductors and capacitors, may be easily incorporated using the existing elements in the SPICE code. Predicted results for MTL's using the method are compared to those of the time-domain to frequency-domain transformation and finite difference-time-domain (FDTD) methods     

Coupled mode analysis of forward and backward coupling in multiconductor transmission lines

The nonorthogonal coupled mode theory is extended to the analysis of multiconductor transmission lines by including backward coupling. Coupling coefficients are expressed as overlap integrals of the eigenfields and currents belonging to individual lines. These eigenmode solutions are calculated using the finite-difference time-domain method, which can provide a broadband solution through a single simulation. General termination conditions are given, and scattering parameters of a multiconductor transmission line can be obtained directly by solving the coupled mode equations subject to these termination conditions. As illustrative examples, several configurations of coupled microstrip lines are analyzed, and numerical results are presented. It is observed that both the forward and backward coupling results agree fairly well with results from Advanced Design System Momentum software.     

A static study of multilayered multiconductor transmission lines

Accurate knowledge of passive MIES and MMIGS has become as important as knowledge of active components. A rather classical method of analysis of multi-dielectric multistrip transmission lines is presented. This analysis, restricted to the quasi-static approach, is based on a variational method in the discrete spectral domain, combined with the transverse transmission line method devoted to the calculation of Green’s functions. This work, devoted only to the study of the distributed parameters of the structures, i.e. in any transverse section, is followed by a complete modal analysis with respect to the direction of propagation and the possible boundary conditions at the terminals. These calculations consist actually mostly of an eigenvalue problem. They are carried out analytically as far as possible by means of a block matrix algebraic formalism particularly well suited to the problem. The mode impedances and the impedance matrix are obtained analytically in a general manner. All the parameters of new structures with four conductors are completely made explicit.     

Electromagnetic coupling to transmission lines under complex illumination

Electromagnetic coupling to transmission lines under complex illumination is studied. The proposed method relies on the plane wave spectrum representation of the excitation fields and on the complex equivalent length formalism. Results concerning the mathematical expectation of the induced voltage and of the maximal available power at the transmission line terminations are derived.     

Analysis of lossy multiconductor transmission lines using theasymptotic waveform evaluation technique

A method is described for the transient analysis of lossy coupled transmission line networks with nonlinear elements. The method combines the asymptotic waveform evaluation technique with a piecewise decomposition algorithm. Two to three orders of magnitude speedup can be achieved relative to previously published methods with comparable accuracy. The method is useful for delay and crosstalk simulation of high speed VLSI interconnects     

A new approach for closed-form transient analysis of multiconductor transmission lines

A novel closed-form model for multiconductor transmission lines is presented. The proposed model is derived from the analytical characterization of half-T ladder networks, which using closed-form polynomials (named DFF and DFFz), allow one to exactly extract poles and residues of the two-port representation of multiconductor transmission lines, thus, generating a time domain macromodel that can be incorporated in a circuit simulator. Since the model is derived from a stable and passive equivalent network, its stability and passivity are strictly preserved. Simulation results for one, two, and three-conductor transmission lines with linear and nonlinear terminations are presented, confirming the validity of the proposed model.     

Time-domain response of multiconductor transmission lines

Evaluation of the time-domain response of multiconductor transmission lines is of great importance in the analysis of the crosstalk in fast digital circuit interconnections, as well as in the analysis of power lines. Several techniques for the computation of the line response, starting from the known circuit-theory parameters, are presented and evaluated. These methods are: time-stepping solution of the telegrapher equations, modal analysis in the time domain, model analysis in the frequency domain, and a convolution technique which uses line Green's functions. The last method can treat the most general case of lossy transmission lines with nonlinear terminal networks. Numerical and experimental results are presented to illustrate these techniques and to give insight into the crosstalk problems in fast digital circuits.     

多导体传输线瞬态响应研究

随着多导体传输线内各导体之间间距的减小, 导体之间的近邻效应对传输线的分布参数和传输特性的影响越来越大.为此, 我们针对三种典型的传输线结构, 分别建立了基于矢势有限元方法分析的多导体传输线的模型, 并分析了近邻效应对磁通密度和分布电感的影响.利用提出的方法计算了同轴传输线的单位长度分布电感, 并将它与采用解析方法得到的结果进行比较来证明该方法的正确性.计算双线传输线在不同间距时的单位长度电感, 与理论分析得到的结果相比较验证了导线间距越小, 近邻效应对单位长度电感的影响越大.最后, 计算考虑了近邻效应的耦合微带线的电感矩阵, 并将它与其他不考虑近邻效应的方法得到的结果相比较, 说明近邻效应对传输线电感矩阵的影响.     

A generalized framework for hybrid simulation of multi-component structures using iterative field refinement

When applying computational simulation techniques to scattering or radiation problems, it is often possible to decompose a complicated geometry into simpler elemental structures (i.e., a helicopter rotor system into its individual blades). By then simulating each component separately, a given problem can be decomposed into smaller and more manageable components, as long as account is taken of the coupling between each component. To implement such coupling, this paper describes a generalized iterative field refinement (IFR) framework, and demonstrates how it can be used as a basis for many hybrid approaches. Within this framework, IFR can also be used to accelerate simulation of geometries made up of rotated, translated, reflected, or replicated versions of a given structure. Several examples are given to show that an approach built around IFR reduces total computation time while allowing the combination of different analysis methods in treating each of the separate components comprising the structure.     

不均匀多导体传输线的瞬态分析

针对越来越严重的信号畸变和线间耦合问题,应用时域有限差分法（Finite Difference Time Domain,FDTD）建立了不均匀多导体传输线的仿真模型,并通过MATLAB编程对不均匀多导体传输线两端的电压响应进行了仿真分析.在此基础上,理论说明了各端口瞬态响应的波形特点.结果表明了时域有限差分法用于分析多导体传输系统电磁兼容问题的正确性和有效性,为电磁干扰的预测提供了有价值的参考信息.     

一种多导体传输线瞬态响应时间步积分法

针对时域有限差分法分析非均匀有损耗多导体传输线瞬态响应的差分振荡问题,提出一种多导体传输线瞬态响应的时间步积分方法。该方法对不等长非均匀有损多导体传输线建模时,无需对耦合传输线进行解耦,能够较方便地求解耦合状态下的不等长非均匀有损多导体传输线系统。所提方法首先对电波方程中的空间微分算子进行差分离散,然后采用梯形积分法对时间微分算子进行积分,最终得到分析不等长非均匀有损多导体传输线瞬态响应的时间步积分算法。该算法不仅应用于不等长非均匀有损多导体传输线模型进行数值计算和理论分析,并对传输线终端端接线性负载和非线性负载的两种情况进行仿真验证。仿真结果表明该方法是有效的。     

圆柱腔内多导体传输线的瞬态电磁响应

为提高系统抗强电磁脉冲毁伤能力,采用时域有限差分法(Finite Difference Time Domain, D)和通用电路仿真器(SPICE)相结合的协同仿真方法,以圆柱腔内由单导线、双绞线、普通双线和同轴线组成的线束为研究对象,重点研究了导线类型、导线间距、捆扎和RC滤波电路对耦合特性的影响.结果表明:耦合系数受腔体和传输线的双重影响,同轴线耦合系数较其他两类线缆降低约40 dB;线间相互屏蔽是捆扎降低耦合系数的主要原因;随着导线间距增大,耦合系数幅值增大;RC滤波电路是降低电磁耦合的有效手段.所得结论对电子系统进行抗电磁脉冲加固具有重要意义.     

Analysis of multiconductor transmission lines using the MacCormack method

I. Introduction With the increasing signal speed and decreasing feature size of modern high-speed integrated circuits, the effects of transmission lines, such as delay, crosstalk, and signal distortion, become very impor- tant[1?3]. Coupling between transmission lines must be considered in circuit analysis. When multicon- ductor transmission lines are studied, they are usu- ally decoupled first[4?9]. The decoupling processes are similar and all have the diagonalization of pa- rameter matrices…     

Sensitivity analysis of multiconductor transmission lines andoptimization for high-speed interconnect circuit design

Sensitivity analysis of multiconductor transmission lines is derived from a new, all-purpose multi-conductor transmission line model in both frequency domain and time domain. Computer implementation of this new model as well as the sensitivity analysis has been completed. It enables efficient, accurate simulations of interconnect circuit responses as well as sensitivity analysis with respect to both electrical and physical transmission line parameters. By applying sensitivity analysis to high-speed interconnect circuit design, design variables are optimized to achieve simultaneous minimization of crosstalk, delays and reflections at desired nodes in the circuit without violating any indispensable design rules. Numerical examples are presented to demonstrate the validity of the proposed sensitivity analysis and illustrate its application to the optimization of high-speed interconnect circuit design     

Approximate solution for propagation modes on lossy multiconductor transmission lines in inhomogeneous media

The letter gives an approximate solution for wave propagation on a system of lossy multiconductor transmission lines with small losses. The solution leads to a general expression for the attenuation factor matrix. The expression gives a correct result for the cases of two and three conductors and can be used for any number of conductors.     

Quick quasi-TEM analysis of multiconductor transmission lines withrectangular cross section

This paper presents an efficient and accurate procedure for computing the quasi-static matrix parameters ([C], [L], [G], and [R]) of rectangular-shaped conductors embedded in a multilayered dielectric medium over an infinite ground plane. An additional top ground plane can also be considered., The problem is formulated in terms of the space-domain integral equation for the free-charge distribution on the slab conductor surfaces. The spatial Green's function is computed from its spectral counterpart using system identification techniques [Prony's method or matrix pencil method (MPM)]. The integral equation is solved by means of a Galerkin scheme employing entire domain basis functions. This results in a small matrix size. In addition, the quasi-analytical evaluation of the entries of the Galerkin matrix leads to a very efficient and accurate computer code. A detailed study on the convergence and accuracy of the method has been included     

Adaptive transient solution of nonuniform multiconductor transmission lines using wavelets

This paper presents a highly adaptive algorithm for the transient simulation of nonuniform interconnects loaded with arbitrary nonlinear and dynamic terminations. The discretization of the governing equations is obtained through a weak formulation using biorthogonal wavelet bases as trial and test functions. It is shown how the multiresolution properties of wavelets lead to very sparse approximations of the voltages and currents in typical transient analyzes. A simple yet effective time-space adaptive algorithm capable of selecting the minimal number of unknowns at each time iteration is described. Numerical results show the high degree of adaptivity of the proposed scheme.     

Comments on "A SPICE model for multiconductor transmission lines excited by an incident electromagnetic field" [and reply]

In a recent paper, C.R. Paul (see ibid., vol.36, p.342, 1994) discusses the concept of using the SPICE circuit analysis code for simulating field-to-wire coupling. He may not be aware that similar work has already been undertaken. A paper by Broyde et al. (1991) appears to be the first published implementation of this idea. The present comments on Paul's mostly theoretical paper emphasize some practical aspects of the simulation of EMC problems using a SPICE simulation program when multiconductor transmission lines (MTL) models are implemented. C.R. Paul responds to the comments.