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Nowadays, after more than a century of inconsiderate divergence between electromagnetic and mechanical field theories, we find it hard to bring them together. This can be best exemplified by the problematic status of the electrodynamics of deformable media. The blame can be laid mainly on the limitations of the underlying theoretical frameworks and on the practitioners’ education, too narrow to bridge...
In this article, we describe two types of conservative variational techniques that aim at improving the use of FDTD methods for the treatment of complex geometries with time dependent Maxwell’s equations.
RF circuits and systems are gaining importance because we are moving further into a society where information is very important and should be available any time and anywhere. In this paper we give an overview of RF circuit simulation with an emphasis on noise simulation which is important functionality for RF designers. Due to the high frequency signals, the standard circuit formulation using Kirchhoff...
We review some recent extensions of the Finite Integration Technique (FIT), which is known to be a generalization of the Finite Difference Time Domain (FDTD) method. Some shortcomings of the standard formulation are discussed which limit the applicability or at least the efficiency of the time domain variant of FIT. The novel developments which are proposed in this paper cover both the basic geometrical...
The paper explores a class of “Finite Element Difference” (FED) schemes with Finite Difference-type data structures but based on Finite Element — variational principles. Curved material boundaries are approximated algebraically on relatively coarse regular rectangular or hexahedral grids by a judicious choice of local approximating functions, rather than geometrically on conforming meshes. The grids...
In refined network analysis, a compact network model is combined with drift-diffusion models for the semiconductor devices which are part of the network, in a multiphysics approach. For linear RLC networks containing diodes as distributed devices, we construct a mathematical model that combines the differentialalgebraic network equations of the circuit with elliptic boundary value problems modelling...
Electric circuits designers are frequently interested in the transient behaviour of the designed circuit. A common method for time integration of the Differential Algebraic circuit Equations (DAE) is the Backward Differentiation Formula (BDF) method. In 1983, J. Cash proposed the Modified Extended BDF (MEBDF) method, which combines better stability properties and higher order of convergence than BDF,...
Thermal effects influence the electrical behaviour of circuits more and more. Therefore it is necessary to take power dissipation and temperature evolution into account. In order to analyize large systems of integrated circuits, this has to be realized very efficiently. Thus we introduce a thermal network model consisting of 0D and 1D thermal elements approximating the full heat aspect, but keeping...
For solving sparse linear systems from circuit simulation whose coefficient matrices include a few dense rows and columns, a parallel Bi-CGSTAB algorithm with distributed Schur complement (DSC) preconditioning is presented. The parallel efficiency of the solver is increased by transforming the equation system into a problem without dense rows and columns as well as by exploitation of parallel graph...
This paper focuses on the development of a model to obtain qualitative insight in the behaviour of large, but finite, phased arrays of microstrip antennas. This model concerns a finite array of simple elements, namely perfectly conducting, infinitely thin, narrow rings, excited by voltage gaps and positioned in free or half space. The currents on the rings, and from that the electromagnetic field,...
The idea of modelling space as two interacting equivalent networks, one for currents, one for magnetic fluxes, pervades computational electromagnetics since its beginnings. The Yee scheme, the TLM method, can thus be interpreted. But this is also true of finite element- or finite volume-inspired more recent proposals, as we show, so the idea is not incompatible with “unstructured” meshes. Yet, meshes...
A novel substrate coupling simulation tool named SubCALM is presented. It is well suited to floorplanning of large mixed-signal designs since it exploits the boundary element method and contains a Poisson solver based on a hierarchical O(n) conjugate gradient algorithm. Sophisticated preconditioners are applied, which further increase the computation speed by a factor of about 10. The approach is...
Widely seperated time scales appear in many electronic circuits, making analysis with the usual numerical methods very difficult and costly. In this article we present a quasilinear system of partial differential equations (PDE) of first order, where the time scales are treated seperately. The PDE corresponds to the system of differential-algebraic equations (DAE) describing the electronic circuit...
In this work we deal with the numerical simulation of thermal oxidation in silicon device technology. This application is a complex coupled phenomen, involving the solution of a diffusion-reaction problem and of a fluid-structure interaction problem. Suitable iterative procedures are devised for handling nonlinearities and strong coupling between the sub-problems to be solved. In particular, we propose...
Nonlinear transient eddy current simulations require the solution of nonlinear differential-algebraic systems of equations of index 1, for which linearimplicit time marching methods of Rosenbrock-type are proposed. These methods avoid the iterative solution of nonlinear systems within each time step due to their built-in Newton procedures. Embedded lower order schemes allow an error-controlled adaptive...
The finite element model of a superconductive dipole magnet is equipped with a specialised conductor model which accounts for the inter-strand currents caused by the ramping of the magnet without explicitly meshing the individual strands.
New modeling technology is developed that allows engineers to define the frequency range, layout parameters, material properties and desired accuracy for automatic generation of simulation models of general passive electrical structures. It combines electromagnetic (EM) accuracy of parameterized passive models with the simulation speed of analytical models. The adaptive algorithm does not require...
Magnetic circuits can be represented with a topological dual circuit. In the dual circuit, flux paths are modelled by hysteretic permeances instead of reluctances. Hysteresis effect is taken into account by using the Jiles-Atherton (JA) approach. In addition, iron losses due to eddy current are also included to the model. Comparison of simulated results with the experimental results from a core type...
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