Perturbation analysis of nonlinear responses caused by transverse modes in AlN FBAR based on 2D scalar wave model

This paper describes perturbation analysis of nonlinear signal generation in apodized film bulk acoustic resonators using a multi-branch LCR equivalent circuit where all necessary simulation parameters are derived by the two-dimensional (2D) scalar wave model. Nonlinear signals are evaluated by adding two voltage sources representing nonlinear strain and electric flux, and their amplitude is determined by currents in the circuit for linear analysis. Simulated second and third harmonic responses agree well with experimental ones. The magnification mechanism of spurious resonances is also discussed.