| 摘要 |
To reduce frequency variations caused by a change in frequency constant and suppress unnecessary vibrations in the case where the frequency constant of a piezoelectric substrate has a gradient. A piezoelectric resonator has vibrating electrodes 4 and 5 facing each other, which are formed on two major surfaces of a piezoelectric substrate 1 a, and trapped vibrations are generated between the two vibrating electrodes. The piezoelectric substrate 1 a has a constant thickness. The frequency constant of the piezoelectric substrate 1 a has a gradient in a surface direction. The vibrating electrodes 4 and 5 are formed to have a gradient thickness so that the thickness gradually increases as the frequency constant of the piezoelectric substrate increases. By forming the vibrating electrodes to have a gradient thickness, unnecessary in-band vibrations are suppressed, and frequency variations are reduced.
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