Nonlinear effects of electrode and Bragg reflector materials in BAW resonators

This work presents a broadband characterization and modeling of the second harmonic nonlinear response in Bulk acoustic wave (BAW) resonators. The proposed circuit model is based on the constitutive equations describing the behavior of all materials used on the different layers of the resonator. These constitutive equations are extended for both the linear and nonlinear domain, and allow to explain all the features observed in the nonlinear response over all the characterized bandwidth. This circuit model is used to explain the nonlinear effects occurring in two different BAW resonators, and concludes that in addition to the well-known nonlinear behavior of the main piezoelectric layer, other layers of the Bragg mirror also contribute to the overall nonlinear response.