Selective normal mode excitation in multilayer thin film bulk acoustic wave resonators

A method for selective normal mode excitation in thin film bulk acoustic wave resonators, based on multilayer structures with any number of ferroelectric films in the paraelectric phase, is presented. The possibility to control the excitation of thin film bulk acoustic resonators' normal modes by simultaneous manipulating both the polarities and the magnitudes of the dc bias voltages applied to the ferroelectric layers is demonstrated. The proposed method was verified using the Lakin's model, modified to describe the electro-mechanical behavior of a structure with four active ferroelectric layers