Multiphysics Modeling of BAW Filters

A novel approach for multiphysics modeling of BAW filters is presented allowing accurate and at the same time efficient modeling of BAW filters at high power levels. The approach takes the different types of losses and their spatial distribution into account in order to provide the required input for thermal simulation. The temperature distribution determined by thermal simulation is used to modify the geometry and the layer stack of each single resonator of the filter. In this way the required input for modeling of electromagnetic and acoustic behavior at high power level is generated. Moreover, the influence of the nonlinear behavior on the frequency shift of the resonance frequency is investigated. The high accuracy of the modeling approach is verified by measurements of the S-parameters and the temperature distribution by infrared thermography during high power loads.