Catálogo de publicaciones - libros

The paper presents a method for generating filter transfer functions optimized in respect to a wide range of behavioral and implementation criteria. The optimization engine is the SQP algorithm, with the main parameters provided by a genetic algorithm tailored to this application.

The paper presents basic principles of the thermal networks method. Modeling of network elements has been shown for convection and radiation. A concept of hierarchical thermal network models for complex geometries has been explained. A formulation of a mass transfer model and a new iterative method of coupling ventilation and thermal networks have been introduced. The last section includes an example of the thermal network computation and a comparison with test results.

In most applications large integrated circuits comprise subcircuits of different functionality causing heterogeneous transient behaviour. Multirate methods exploit local latency by using different stepsizes according to the subcircuits' activity levels at each time point. Following the idea of mixed multirate for ordinary differential equations a hierarchical ROWbased multirate method that can deal with an arbitrary number of subcircuits is developed.

The (nonlinear) transient analysis of electrical circuit models plays an important role in circuit design. Multirate time integration can be able to achieve the same accuracy for much lower costs. An essential assumption is the existence of a good partition of the circuit in a slow and fast part. This paper describes how this can be done automatically.

A multidimensional model yields an alternative strategy for the numerical simulation of frequency-modulated signals. Thus the differential algebraic equations (DAEs), which describe an electric circuit, change into warped multirate partial differential algebraic equations (MPDAEs). Houben [6] introduced an approach for solving efficiently initial-boundary value problems of such MPDAE systems. Thereby, envelope-modulated solutions of the DAEs are reproduced. In this paper, the technique is analysed for obtaining quasiperiodic solutions of the DAEs. The crucial question is if biperiodic solutions of the MPDAEs are generated automatically by Houben's approach provided that the initial values of a biperiodic solution are applied.

The paper presents a historical review and the current state-of-the-art of the Finite Integration Technique (FIT), method which has been successfully used for almost 30 years for the solution of electromagnetic field problems. The presented applications are in the range of high-end RF and microwave technologies.

An efficient methodology to extract reduced order models for electromagnetic devices is presented. To solve field-circuits coupled problems, the electromagnetic field equations are discretized by the dual Finite Integration Technique (dFIT), a numerical method which allows the accuracy control of the extracted parameters. Several techniques are used to accelerate the extraction process, such as minimal virtual boundary, minimal mesh and minimal frequency samples set. The frequency characteristic of the device is then approximated by a rational function of appropriate degree in order to extract the reduced order model and its SPICE equivalent circuit. The behavior of the synthesized model extracted with proposed algorithm, in the case of passive on-chip devices placed on silicon substrate shows good agreement with respect to the measurements.

The paper describes the application of the Newton method in conjunction with the Finite Integration Technique. Even on orthogonal grid pairs, the material matrices become nondiagonal and lead to higher algorithmic complexity. A uni-directional version of these matrices provides a computationally inexpensive alternative. The paper compares and discusses the two algorithms' order of convergence and their computational complexity.

Two armatures of a linear actuator are discretized by the Finite Integration Technique at two independent three-dimensional Cartesian grids. The fixed and the moving armature are coupled at a sliding surface, situated in the middle of the air-gap. The moving armature is displaced in -direction, on a plane parallel to the coupling plane and the generated forces are calculated. The mobile armature is made from laminated iron, in which the eddy current losses are negligible, but the fixed armature is made from massive iron in which the eddy currents have a significant influence. A coupled transient simulation is carried out, considering both the magnetic and the mechanic behavior of the actuator.

An efficient methodology to extract reduced order models for electromagnetic devices is presented. To solve field-circuits coupled problems, the electromagnetic field equations are discretized by the dual Finite Integration Technique (dFIT), a numerical method which allows the accuracy control of the extracted parameters. Several techniques are used to accelerate the extraction process, such as minimal virtual boundary, minimal mesh and minimal frequency samples set. The frequency characteristic of the device is then approximated by a rational function of appropriate degree in order to extract the reduced order model and its SPICE equivalent circuit. The behavior of the synthesized model extracted with proposed algorithm, in the case of passive on-chip devices placed on silicon substrate shows good agreement with respect to the measurements.