Study On Electro-Thermal Simulation Of Planar Microstrip Circuits

In recent decades,with the rapid increase of the computer technology in the computing speed and memory capacity,the field of computational electromagnetism has been rapidly growing.Method of moments,finite element method,finite difference time domain algorithm and so on,provide a great help for the field of electromagnetic and microwave.Among them,the finite difference time domain algorithm is the most widely used method.This article will establish an effective multiphysics numerical analysis method for microstrip circuits.In this thesis,three aspects will be studied.The first aspect,the electric problem of microstrip circuit will be studied.Firstly,the finite difference form of the telegraph equation is given,including lossless circuit and loss circuit.Then the frequency-dependent characteristic of transmission line and circuit is taken into account.The finite-difference time-domain formula based on the frequency-dependent equivalent circuit model is adopted.This method has the advantages of simple modeling,low computational complexity and good precision.The second aspect,the rapid simulation of three-dimensional temperature field is studied.Firstly,the finite difference method is introduced to solve the steady state temperature field problem.The central difference scheme is used to deal with the second order derivative of the temperature to the space variable.At the same time,three kinds of boundary conditions and treatment are discussed for steady state problem.Then the alternating direction implicit(ADI)method is employed for the transient simulations of temperature field in 3-D structure.Since the ADI method avoids solving the original complicated equation,the computational resources are reduced significantly and it holds the linear computational complex.Compared with traditional methods,it is much more efficient.In addition,the ADI approach is unconditionally stable.Finally,the simulation results of steady state and transient state are solved by the example of multilayer structure,Compared with the result of commercial simulation software COMSOL,the accuracy and efficiency of the method are verified.The third aspect,This paper studies the rapid electro-thermal simulation of planar microstrip circuits.Firstly,the temperature rise model of microstrip line is given.And then using the heat transfer line theory to solve the problem of a large difference along the line of microstrip circuit for temperature distribution.The idea is to calculate the electrical losses(including conductor loss and dielectric loss)as a heat source,using heat transfer line theory to calculate temperature.The accuracy of the method is verified by the comparison with the commercial software.At the same time,the simulation time has obvious advantages.