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We introduce a novel parameterization scheme based on the generalized method of characteristics (MoC) for macromodels of transmission-line structures having a cross section depending on several free geometrical and material parameters. This situation is common in early design stages, when the physical structures still have to be finalized and optimized under signal integrity and electromagnetic compatibility constraints. The topology of the adopted line macromodels has been demonstrated to guarantee excellent accuracy and efficiency. The key factors are propagation delay extraction and rational approximations, which intrinsically lead to a SPICE-compatible macromodel stamp. We introduce a scheme that parameterizes this stamp as a function of geometrical and material parameters such as conductor-width and separation, dielectric thickness, and permettivity. The parameterization is performed via multidimensional interpolation of the residue matrices in the rational approximation of characteristic admittance and propagation operators. A significant advantage of this approach consists of the possibility of efficiently utilizing the MoC methodology in an optimization scheme and eventually helping the design of interconnects. We apply the proposed scheme to flexible printed interconnects that are typically found in portable devices having moving parts. Several validations demonstrate the effectiveness of the approach. Index Terms--Interpolation, parametric modeling, rational approximation, transmission line modeling.

We present a systematic methodology for the electromagnetic modeling of interconnected digital I/O ports. Digital drivers and receivers are represented through behavioral models based on radial basis functions expansions. Such a technique allows a very accurate representation of nonlinear/dynamic effects as well as switching behavior of real-world components by means of carefully identified discrete-time models. The inclusion of these models into a finite-difference time-domain solver for full-wave analysis of interconnected systems is presented. A rigorous stability analysis shows that use of nonlinear/dynamic discrete-time models can be easily integrated with standard full-wave solvers, even in the case of unmatched sampling time. A set of numerical examples illustrates the feasibility of this method. Index Terms--Behavioral models, digital I/O ports, finite-difference time-domain (FDTD) methods, nonlinear circuits, radial basis functions, transient analysis.

In this work, field excitation and bulk current injection (BCI) on a wire bundle are analytically compared. The equivalence of the two excitation techniques is investigated in order to ascertain the validity of using current injection testing rather than radiated immunity testing for an equipment connected at one end of the bundle. The wire bundle is modeled as a multiconductor transmission line which, throughout the analysis, is treated as a multiport device. The equivalence is discussed by comparing the effects that the sources produce at the terminal ports, with the aim to control the clamp voltage in order to match the incident field characteristics. This approach yields general results, which are not affected by any assumptions on the terminal networks. It is shown that one injection probe is not sufficient to assure the equivalence in the general case, but it is possible, although practically difficult, to achieve this result by employing two injection probes. In the simpler but more specific case of linear terminations, a test procedure is proposed which allows equivalence by using a single injection current probe. Since the ideal BCI procedure must represent a worst-case stress analysis for the equipment under test, the possibility of adopting BCI tests to reproduce the upper envelope of the radiation-induced currents is also investigated. In this case practical difficulties are evidenced and arise from the need of feeding the injection probes with a complicated frequency-dependent power distribution.

This paper proposes a circuit model for lossy multiconductor transmission lines (MTL's) suitable for implementation in modern SPICE simulators, as well as in any simulator supporting differential operators. The model includes the effects of a uniform or nonuniform disturbing field illuminating the line and is especially devised for the transient simulation of electrically long wideband interconnects with frequency dependent per-unit-length parameters. The MTL is characterized by its transient matched scattering responses, which are computed including both dc and skin losses by means of a specific algorithm for the inversion of the Laplace Transform. The line characteristics are then represented in terms of differential operators and ideal delays to improve the numerical efficiency and to simplify the coding of the model in existing simulators. The model can be successfully applied to many kinds of interconnects ranging from micrometric high-resistivity metallizations to low-loss PCB's and cables, and can be considered a practical extension of the widely appreciated lossless MTL SPICE model, of which maintains the simplicity and efficiency.