| 摘要 |
PROBLEM TO BE SOLVED: To provide a ladder SAW filter in which surface acoustic waves are propagated in an isotropic manner, which has no occurrence of different propagation speeds of the surface acoustic waves caused by an arrangement direction of an IDT, and which has almost no deterioration of the broadband characteristics. SOLUTION: A piezoelectric layer 3 is formed by gathering a large number of crystal grains in an isotropic shape in a plan view on a substrate 2. A plurality of comb-shaped electrodes 4 having one array direction respectively on the piezoelectric layer 3. The ladder SAW filter 1 is doped in which at least one array direction of the comb-shaped electrode 4a among the comb-shaped electrodes is different from the array directions of the other comb-shaped electrodes 4b, 4c. COPYRIGHT: (C)2004,JPO
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