424 research outputs found
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.
An Adaptive Sampling Technique for Passivity Characterization and Enforcement of Large Interconnect Macromodels
A Perturbation Scheme for Passivity Verification and Enforcement of Parameterized Macromodels
This paper presents an algorithm for checking and enforcing passivity of
behavioral reduced-order macromodels of LTI systems, whose frequency-domain
(scattering) responses depend on external parameters. Such models, which are
typically extracted from sampled input-output responses obtained from numerical
solution of first-principle physical models, usually expressed as Partial
Differential Equations, prove extremely useful in design flows, since they
allow optimization, what-if or sensitivity analyses, and design centering.
Starting from an implicit parameterization of both poles and residues of the
model, as resulting from well-known model identification schemes based on the
Generalized Sanathanan-Koerner iteration, we construct a parameter-dependent
Skew-Hamiltonian/Hamiltonian matrix pencil. The iterative extraction of purely
imaginary eigenvalues ot fhe pencil, combined with an adaptive sampling scheme
in the parameter space, is able to identify all regions in the
frequency-parameter plane where local passivity violations occur. Then, a
singular value perturbation scheme is setup to iteratively correct the model
coefficients, until all local passivity violations are eliminated. The final
result is a corrected model, which is uniformly passive throughout the
parameter range. Several numerical examples denomstrate the effectiveness of
the proposed approach.Comment: Submitted to the IEEE Transactions on Components, Packaging and
Manufacturing Technology on 13-Apr-201
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
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