A novel approach for multiphysics modeling of bulk acoustic wave (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 (EM) and acoustic behavior at high power level is generated. The high accuracy of the modeling approach is verified by the measurements of the S-parameters and the temperature distribution by infrared thermography during high-power loads. Moreover, the influence of the nonlinear behavior on the frequency shift of the resonance frequency is investigated. For this purpose, a parameterized nonlinear Mason model has been combined with a 3-D EM finite-element method and the required nonlinear material parameters were determined by fitting simulation results to the measured polyharmonic distortion model (X-parameters) of a BAW resonator.
This paper reviews the latest developments in microwave acoustic wave devices. After an introduction and brief history of bulk acoustic wave (BAW) and surface acoustic wave (SAW) devices, a review is given for guided SAWs and XBARs -two new technologies, which are promising for future 5G applications. Following this, we discuss recent simulation techniques, such as 3D finite element method (3D FEM) and simulation of nonlinearities, as well as filter synthesis. Next, a review on tunable and reconfigurable acoustics is given. Finally, we present the latest developments in microwave acoustics for millimeter-wave (mm-wave) operation as well as BAW oscillators.INDEX TERMS Bulk acoustic wave (BAW) devices, filter, filter-synthesis, front-end, high power, MTT 70th Anniversary Special Issue, multiplexer, nonlinearity, resonator, surface acoustic wave (SAW) devices.
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