A novel ab-initio finite difference-based method for convenient implementation of the mass-loading effect in microacoustic devices

摘要

Accurate, robust and accelerated implementation of the mass-loading effect in non-periodic micro-acoustic device structures continues to be a challenging undertaking. Existing works, nearly exclusively, apply the (Finite Element Method) FEM / (Boundary Element Method) BEM hybrid technique to periodic structures. Application of the FEM/BEM to non-periodic structures is excessively time consuming and leads to comparatively inaccurate results. On the other hand the BEM/BEM monolithic technique, while being impressively accurate, is extraordinarily cumbersome to formulate, and computationally very expensive to handle realistic device models, as the present authors have discussed elsewhere. This work presents a novel technique based on the (Finite Difference Frequency Domain) FDFD / BEM hybrid formulation. The breakthrough result stems from an easy-to-implement formulation of the edge-effects to an arbitrary accuracy and the complete elimination of the corner points from the analysis. These distinguished properties render the implementation of the mass-loading effect amenable to realistic models and parallel computing at the same time. Based on the tables provided for the partial derivatives, the effort for developing the code is negligible: existing software can easily be augmented to account for the mass-loading effect. Numerical results are thoroughly tested by an independently-developed FEM-based package. Excellent numerical results with predictable figures of accuracy have been achieved. The contribution concludes with a brief discussion of the relevance of the conservative FDFD implementation of the mass-loading effect to account for arbitrarily-shaped electrode bounding surfaces.