Modelling of SAW filter based on ZnO/diamond/Si layered structure including velocity dispersion

A simulator based on the coupling of mode (COM) theory, previously develope d for modelling the bulk substrate surface acoustic wave (SAW) devices, was modified to be adapted for layered structures. The frequency response of Z nO/diamond/Si-SAW filter was calculated and the results were compared with experimental ones extracted from the literature. A good agreement is obtain ed for the frequencies within and close to the pass-band of the filter. Out side of this pass-band, the experimental frequency response exhibits an asy mmetry, which is not reproduced by the simulation. This asymmetry is attrib uted to the dispersion, as a function of frequency, of SAW velocity (V-P) a nd electromechanical coupling coefficient (K-2), which cannot be neglected in the case of layered structures. In the original program developed for bu lk structures, K-2 and V were assumed to be constant. To take into account the effect of dispersion, the program was modified by the introduction of a dispersive model. The confrontation between the results obtained by simula tion, including the dispersive model, and by experimental measurements show s a good agreement. (C) 2000 Elsevier Science B.V. All rights reserved.