Accélération du temps de simulation des structures électromagnétiques planaires et tridimensionnnelles à très hautes fréquences

Abstract

With the conquest of new high frequency bands and the increasing complexity of modern wireless circuits capable of fitting an entire front-end radio with high integration level within tiny volumes, the use of electromagnetic simulation based on numerical methods such as the finite-element method (FEM), the finite difference method (FDTD) method and the method of Moments (MoM) is an essential solution for challenges mitigation. In this context, an accurate prediction of the electrical performance comes at the cost of high execution time and hardware resources despite the great advances in computational power over the past two decades. Thus, the development of new algorithms and methods in order to accelerate electromagnetic simulation with these methods is still relevant. In this context, researches that have been carried out in connection with this PhD thesis were divided into two main parts. During the first part, the focus was on fast frequency sweep based on the order model reduction techniques (MORe) applied to the FEM method. These techniques start with one complete FEM solution only at given frequency, usually called expansion frequency, in order to approximate all FEM solutions at frequencies surrounding this expansion frequency. These techniques suffer from two major issues, namely (i) The lack of reliable and efficient method for determining the size of the reduced model (ii) Multipoint MORe techniques estimate approximation error for additional expansion frequencies through computationally inefficient algorithms. Two contributions have been proposed to solve issue (i). The idea behind the first contribution is to increment the size of the reduced model in an adaptive manner based on an estimate of the approximation error at each frequency. The second contribution is a new approach that determines the size of the reduced model a priori based on an estimation of the expected acceleration time of the rapid frequency sweep solution in comparison with the regular frequency sweep. The last contribution in the first part of this thesis, is an attempt to find a solution to issue (ii) by considering a decision criterion for adding extra expansion frequencies based on the passivity condition for lossless multiport circuits. All these methods have been validated by application to the "well-conditioned asymptotic waveform evaluation" (WCAWE) and have shown good performances in terms of computation time. The second part of this thesis concerns the MoM. In the first section, a fast generation technique of the MoM interaction matrix between test functions and basis functions called FMG-MP has been proposed. This technique uses the Gauss points of the quadrature integral as evaluation points for the Green’s function and reduces two-dimensional double integrals into a sum of simple and easy to calculate products. The second section of this part was devoted to excitation source modeling for generalized S parameters extraction of planar structures in general and "microstrip" particularly with the MoM.

Date	17 Aug 2017
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Ammar B. Kouki (Supervisor)