| 摘要 |
The present invention is a surface acoustic wave filter that has a laminate comprising a high-acoustic-velocity member, a low-acoustic-velocity film, and a piezoelectric film and that the capability of inhibiting spurious components from being generated. A longitudinally-coupled-resonator-type surface acoustic wave filter (1) in which the surface acoustic wave filter (1) is provided with: a high-acoustic-velocity member (3); a low-acoustic-velocity film (4) provided on the high-acoustic-velocity member (3); a piezoelectric film (5) provided on the low-acoustic-velocity film (4); a plurality of IDTs (6-8) formed on the piezoelectric film (5) along the direction of propagation of the surface acoustic waves, each of the IDTs (6-8) having a plurality of electrode fingers; and reflectors (9, 10). In each of the IDTs (6-8), the finger electrode pitch is substantially uniform. Taking λ to represent the wavelength determined by the finger electrode pitch in the reflectors (9, 10), the inter-electrode-finger-center distance, which is the distance between each of the IDTs (6-8) and an adjacent IDT, is 0.25λ-0.37λ inclusive. |
