Giulio Antonini

Feature selective validation (FSV) for validation of computational electromagnetics (CEM). part I-the FSV method

A goal for the validation of computational electromagnetics (CEM) is to provide the community with a simple computational method that can be used to predict the assessment of electromagnetic compatibility (EMC) data as it would be undertaken by individuals or teams of engineers. The benefits of being able to do this include quantifying the comparison of data that has hitherto only been assessed qualitatively, to provide the ability to track differences between model iterations, and to provide a means of capturing the variability and range of opinions of groups and teams of workers. The feature selective validation (FSV) technique shows great promise for achieving this goal. This paper presents a detailed analysis of the FSV method, setting it firmly in the context of previous comparison techniques; it suggests the relationship between validation of graphically presented data and the psychology of visual perception. A set of applicability tests to judge the effectiveness of computer-based CEM validation techniques is also proposed. This paper is followed by a detailed comparison with visual assessment, which is presented in Part II

Nonorthogonal PEEC formulation for time- and frequency-domain EM and circuit modeling

Electromagnetic solvers based on the partial element equivalent circuit (PEEC) approach have proven to be well suited for the solution of combined circuit and EM problems. The inclusion of all types of Spice circuit elements is possible. Due to this, the approach has been used in many different tools. Most of these solvers have been based on a rectangular or Manhattan representation of the geometries. In this paper, we systematically extend the PEEC formulation to nonorthogonal geometries since many practical EM problems require a more general formulation. Importantly, the model given in this paper is consistent with the classical PEEC model for rectangular geometries. Some examples illustrating the application of the approach are given for both the time and frequency domain.

SPICE equivalent circuits of frequency-domain responses

The paper proposes a method for the synthesis of SPICE-compatible broad-band electrical models of frequency-domain responses approximated by rational functions. First- and second-order equivalent circuits with controlled sources are used as building blocks to generate equivalent circuit representations-totally compatible with commercial circuit solvers - of the frequency-dependent responses. Fundamental properties of the method are discussed and details of its implementation are described. The proposed approach has demonstrated to be suitable for providing equivalent circuits of interconnects, power/ground plane structures and PCB discontinuities.

Variability Analysis of Multiport Systems Via Polynomial-Chaos Expansion

We present a novel technique to perform variability analysis of multiport systems. The versatility of the proposed technique makes it suitable for the analysis of different types of modern electrical systems (e.g., interconnections, filters, connectors). The proposed method, based on the calculation of a set of univariate macromodels and on the use of the polynomial chaos expansion, produces a macromodel of the transfer function of the multiport system including its statistical properties. The accuracy and the significant speed up with respect to the classical Monte Carlo analysis are verified by means of two numerical examples.

EMC characterization of SMPS devices: circuit and radiated emissions model

Since the efficiency of switched mode power supplies (SMPS) is much higher than that of linear power supplies, this type of supply has gained favor among designers and manufacturers. Switching frequencies extend from tens to hundreds of kilohertz with the result that radiation from circuits carrying switched current is becoming more of a problem. This paper addresses the modeling of the converter section of an SMPS in order to calculate the current distribution and the radiated electromagnetic field. The inhomogeneities in the circuit are by equivalent electrical parameters and a technique is introduced to take into account the fictitious effects on radiation due to the electrostatic terms in the dipole equations. The global approach is validated by comparison of the computed results with those measured for a simple and clearly arranged SMPS experimental setup.

A Dyadic Green's Function Based Method for the Transient Analysis of Lossy and Dispersive Multiconductor Transmission Lines

This paper describes a new algorithm for the analysis of multiconductor transmission lines characterized by frequency-dependent per-unit-length parameters. The proposed model is based on studying telegraphers equations as a Sturm-Liouville problem. The open-end impedance matrix is expressed in a series form as an infinite sum of matrices of rational functions, derived from the series form of the dyadic Greens function. The rational form of the open-end impedance matrix allows an easy identification of poles and residues and, thus, the development of a reduced-order system of the interconnect. The pole-residue representation can be synthesized in an equivalent circuit or converted into a state-space model, which can be easily embedded into conventional nonlinear circuit SPICE-like solvers. The numerical results confirm the validity of the proposed modeling technique.

PEEC Modeling of Dispersive and Lossy Dielectrics

In this paper a general formulation is presented for the time-domain partial element equivalent circuit method in a general dispersive medium. The formulation is based on Debye and Lorentz models where the resulting model is passive. The incorporation of such models into a partial element equivalent circuit solver is described by both convolution techniques and equivalent circuits. The new circuit models can be applied in the frequency as well as the time domain. Numerical examples are given to validate the proposed formulation and to show that the proposed method is accurately capturing the physics of dispersive and lossy dielectrics.

Equivalent network synthesis for via holes discontinuities

A methodology is presented for the synthesis of the passive equivalent circuit of via holes in multilayer printed circuit boards. The paper describes the network synthesis starting from the extraction of the poles and residues from the driving point transfer functions for two port networks. The via hole is partitioned into elementary structures assumed not electromagnetically coupled and the scattering parameters for each one of them are evaluated by using a numerical approach suitably validated by comparison with results computed by other independent numerical methods. The equivalent circuit of the complete via hole is given by the cascading of the circuits of the elementary structures. The proposed technique is validated by comparing the computed scattering parameters with those from measurements for real test boards.

PEEC modeling of linear magnetic materials

This paper presents a 3D electromagnetic mod- eling technique that extends the PEEC approach to an- alyze arbitrary inhomogeneous structures constituted by conductors, dielectrics and magnetic materials. The proposed approach, while preserving the topology of PEEC elementary circuit, allows to use the PEEC method to model more general materials (e.g. chiral media, metamaterials) and extends its applicability to power systems involving magnetic materials as well as to RFIC systems requiring modeling of both dielectric and magnetic materials.

Multipoint Full-Wave Model Order Reduction for Delayed PEEC Models With Large Delays

The increase of operating frequencies requires 3-D electromagnetic (EM) methods, such as the partial element equivalent circuit (PEEC) method, for the analysis and design of high-speed circuits. Very large systems of equations are often produced by 3-D EM methods and model order reduction (MOR) techniques are used to reduce such a high complexity. When signal waveform rise times decrease and the corresponding frequency content increases, or the geometric dimensions become electrically large, time delays must be included in the modeling. A PEEC formulation, which include delay elements called τ PEEC method, becomes necessary and leads to systems of neutral delayed differential equations (NDDE). The reduction of large NDDE is still a very challenging research topic, especially for electrically large structures, where delays among coupled elements cannot be neglected or easily approximated by rational basis functions. We propose a novel model order technique for τ PEEC models that is able to accurately reduce electrically large systems with large delays. It is based on an adaptive multipoint expansion and MOR of equivalent first-order systems. The neutral delayed differential formulation is preserved in the reduced model. Pertinent numerical examples based on τ PEEC models validate the proposed MOR approach.