Calculations of parameters of BAW microwave composite resonators

This paper uses available models to calculate the main operating parameters of BAW microwave composite resonators. Although such resonators can be used as devices for characterization of the underlying substrate, they can be expected to reach comparatively good performances if the substrate is made from very low loss material, such as YAG driven into vibration by a thin layer of ZnO or AlN. Operating on very high overtone is then quite feasible and solves many technological issues related to the achievement of actually thin membranes. Also, earlier investigations have shown a surprisingly efficient energy trapping on such resonators. The paper presents first investigations about microwave composite resonators operating around 3 GHz, using existing analytical models and shortly discusses issues attached to a two-dimensional FEM. The authors conclude that this technique should evolve to fully develop its expected benefits and must still be substituted by analytical calculations to allow for accurate calculation of parameters in actual devices. Use of existing model for energy trapping analysis seems possible even for very high overtone numbers.