| 摘要 |
PURPOSE:To obtain a surface acoustic wave resonator with small size, low loss, high Q and high SR by forming an IDT and a reflector with the conductive material of the same film thickness and the same kind and selecting properly the ratio of the IDT period and the reflector period. CONSTITUTION:The ratio LT/g being the IDT period LT to the reflector grating period LR is selected smaller than 1 so as to make the frequency maximizing the reflectance of the reflector close to the frequency maximizing the radiation conductance. Aluminum is used as the conductive material, and the film thickness of 1,000Angstrom or below is selected to improve the etching accuracy and to avoid the deterioration in the SR, Q due to the bulk wave conversion and multiple reflection between electrodes at the end of the IDT and the reflector. Further, the cut angle theta of a crystal rotating Y plate is selected as 32-38 deg.. Thus, the surface acoustic wave energy conversion efficiency between the IDT and the reflector is increased, the resonator with high Q, high SR and low loss is realized, the mass-productivity is improved and miniaturization is attained.
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