Generation of passive macromodels from transient port responses

Abstract: This paper presents a new technique for the generation of linear lumped macromodels from input-output port characterization. A complete set of transient port responses is processed by a new time-domain formulation of the well-known Vector Fitting algorithm. The data processing involves a combination of digital filtering and least squares fitting. Passivity of the obtained macromodel is enforced a posteriori by applying an iterative perturbation technique to the associated Hamiltonian matrix.

Passivity Enforcement via Perturbation of Hamiltonian Matrices

This paper presents a new technique for the passivity enforcement of linear time-invariant multiport systems in statespace form. This technique is based on a study of the spectral properties of related Hamiltonian matrices. The formulation is applicable in case the system input-output transfer function is in admittance, impedance, hybrid, or scattering form. A standard test for passivity is first performed by checking the existence of imaginary eigenvalues of the associated Hamiltonian matrix. In the presence of imaginary eigenvalues the system is not passive. In such a case, a new result based on first-order perturbation theory is presented for the precise characterization of the frequency bands where passivity violations occur. This characterization is then used for the design of an iterative perturbation scheme of the state matrices, aimed at the displacement of the imaginary eigenvalues of the Hamiltonian matrix. The result is an effective algorithm leading to the compensation of the passivity violations. This procedure is very efficient when the passivity violations are small, so that first-order perturbation is applicable. Several examples illustrate and validate the procedure

Adaptive transient solution of nonuniform multiconductor transmission lines using wavelets

Abstract—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 formula-tion 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 al-gorithm 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. Index Terms—Electromagnetic (EM) transient analysis, multi-conductor transmission lines (TLs), wavelet transforms. I

Package Macromodeling via Time-Domain Vector Fitting

Abstract—This paper addresses the construction of lumped macromodels for package structures. A technique named Time-Domain Vector Fitting (TD-VF) is introduced for the identification of the dominant poles of the structure. This method uses as raw data transient excitations and responses at the ports of the struc-ture. These responses are easily obtained from transient full-wave electromagnetic solvers based, e.g., on Finite Differences. The rational approximation can be easily synthesized into a SPICE-compatible subcircuit providing a broadband approximation to the input-output behavior of the package. Index Terms—Circuit extraction, macromodeling, time-domain vector fitting, vector fitting