High Performance Multiphysics Computational Methods And Their Applications For Simulating RF Devices And Large Phased Array Antennas

The continuous progress of wireless communication technology promotes the development of radio frequency(RF)devices in the direction of miniaturization,high frequency and high power density.And RF devices are usually packaged in threedimensional integrated circuits(3DICs)and heterogeneous integrated systems.As RF device feature sizes continue to decrease and integration increases,as well as requirements for higher frequencies and higher power levels,multi-physical effects such as self-heating and thermal stress can no longer be ignored.On the other hand,phased array antennas have fast beam steering and multi-target tracking capabilities,and have been widely used in radar,radio astronomy and fifth-generation mobile communication(5G)base stations.According to the specific application requirements of phased array antennas,the number of antenna elements may reach thousands.At the same time,with the continuous improvement of signal frequency and signal power,the antenna element is getting smaller and smaller,and is packaged in a system-in-package(Si P)together with RF devices and chips in the form of Antenna-in-Package(Ai P).Since many high-power-density components are integrated in a small space,a series of problems such as Joule heating effect,temperature rise and thermal stress are generated,which further affects the performance of the system.Therefore,in their design stage,multiphysics coupled simulation analysis must be carried out to guide their highperformance and high-reliability design.Because 3DICs and heterogeneous integrated systems usually integrate multiple structures of different sizes,the scale of the mesh is huge;while the antenna array model has obvious multi-scale characteristics and contains a large number of elements,especially its feeding network is complex.Therefore,it is crucial to study massively parallel algorithms for multiphysics simulation.This dissertation focuses on the cosimulation method between electromagnetic(EM),thermal and stress.Based on high-performance parallel framework and Chinamade supercomputers,several massively parallel algorithms and solvers have been developed.The main research work and innovative achievements are summarized as follows:1.Based on a high-performance parallel programming framework,studied and developed a parallel multiphysics finite element method(FEM)solver suitable for supercomputer architecture,which realized the numerical calculation of the coupling process between frequency-domain(FD)electromagnetic(EM),transient thermal and thermal stress;compared the calculation results with commercial software and measurement results,and the solver showed high accuracy;using the self-developed solver,multiphysics simulation of different RF devices was carried out,and the influence of temperature and thermal stress on the electrical performance of such devices was analyzed.2.In order to further expand the scale of FD EM-transient thermal-stress coupling calculation,based on the data structure of a high-performance parallel framework,an overlapping domain decomposition method(DDM)is implemented to construct the preconditioned matrix of the Krylov subspace iteration method,and completed solver development.Strong scalability parallel experiment was carried out on supercomputer,and the solver showed high parallel performance;in particular,the self-developed solver was used to analyze the multiphysics coupling effect in millimeter-wave filters,and completed the numerical simulation of EM-thermal-stress coupled processes in a complex Si P.3.The non-overlapping DDM is studied,which is used to construct a block Jacobi iterative scheme.Relying on a high-performance parallel framework,large-scale problems are transformed into several small-scale problems that can be solved in parallel,which improved the scalability of FD EM solutions;a parallel cosimulation solver of FD EM and steady-state thermal is implemented,in which FD EM and steadystate thermal are coupled through Joule heat and temperature-dependent material parameters;the proposed co-simulation solver is compared with commercial software,showed a high degree of confidence;and the solver showed strong performance in parallel experiments;realized the numerical calculation of the multiphysics coupling process of large-scale antenna arrays.4.Based on the supercomputer architecture,the preconditioned Bi CGSTAB iterative method is reconstructed,and the non-overlapping DDM is used to construct the preconditioner,which accelerates the calculation of the FD EM;realized a parallel FD EM-steady-state thermal-stress coupling process,and completed the development of the in-house solver;the strong/weak parallel scalability experiment was carried out on a China-made supercomputer,and the solver showed high parallel performance;using the in-house solver,a challenging antenna array was simulated,increasing the scale of electromagnetic induced multiphysics simulations to 1.2 billion unknowns for the first time.