This paper describes application of the hierarchical cascading technique (HCT) to the 3D FEM analysis of transverse mode behaviors in surface acoustic wave (SAW) devices. Mirror cascading is proposed as a speed up technique for the HCT operation using the general purpose graphic processing unit (GPGPU). Two methods are implemented for the analysis; one is impedance calculation, and the other is calculation of SAW scattering coefficients at boundaries. It is demonstrated that HCT enables rapid calculation for successive simulation with scanning design parameters. Thus, techniques discussed in the paper are quite effective for optimization of device structures. It is also shown that GPGPU can accelerate HCT calculation dramatically, especially for 3D cases discussed in this paper.

This paper proposes an application of a general purpose graphic processing unit (GPGPU) to the finite element method analysis based on the hierarchical cascading technique (HCT). It is proved that GPGPU can accelerate the HCT significantly, especially for large scale problems. Thanks to significant acceleration, full three-dimensional simulation is possible for practical surface acoustic wave (SAW) device structures. Besides admittance curve, the displacement field is calculated. It is shown that SAW scattering occurs at the boundary at busbar spaces between the interdigital transducer (IDT) and reflector regions.

In this paper, we propose the use of the hierarchical cascading technique (HCT) for the finite element method (FEM) analysis of bulk acoustic wave (BAW) devices. First, the implementation of this technique is presented for the FEM analysis of BAW devices. It is shown that the traveling-wave excitation sources proposed by the authors are fully compatible with the HCT. Furthermore, a HCT-based absorbing mechanism is also proposed to replace the perfectly matched layer (PML). Finally, it is demonstrated how the technique is much more efficient in terms of memory consumption and execution time than the full FEM analysis.

This paper describes derivation of an equivalent circuit for nonlinear responses in film bulk acoustic resonators from the first-order perturbation analysis using the piezoelectric constitutive equations with the h-form. For simplicity, electrodes and piezoelectric layer are regarded as a mass and spring in the derivation. Then it is demonstrated that second- and third-order harmonic responses can be simulated well by the circuit. In addition, nonlinearity in the Si substrate is also taken into account, and its impact is discussed. It is also discussed how the frequency dependences vary with the nonlinearity mechanisms as a finding from the derived equivalent circuit.

This paper investigates the influence of coupling between Rayleigh and shear-horizontal (SH) surface acoustic waves (SAWs) on rotated Y-cut LiNbO ₃ to their electromechanical coupling. For the purpose, a coupling-of-mode (COM) model including the coupling between two SAWs is developed, and the coupling influences to their excitation in addition to electromechanical coupling factors are discussed. Then, its validity is confirmed by comparison of its results with the finite-element method analysis. Comparing with the conventional COM shows this extended COM model could fit the complex value area much better in the dispersion curve analysis. After that, variation of COM parameters with the device design is discussed. Then, all COM parameters are fit by polynomial equations and the procedures to find the optimal rotation angle are obtained in terms of the SH mode suppression. It indicates that the optimal angle changes rapidly at certain Cu thickness, which is due to decoupling between two SAW modes. At last, structure based on the low-cut LiNbO ₃ is discussed and the validity of this COM model is further confirmed.