| 摘要 |
An acoustic wave device and a filter are provided to obtain a narrow pass band of the filter by accurately controlling an electrical-mechanical coupling coefficient of the acoustic wave device. An acoustic wave device includes a piezoelectric substrate(12), a first dielectric(24), electrodes(14,16), and an electrode finger. The first dielectric is formed on the piezoelectric substrate. The electrodes initiate an acoustic wave which is formed on the first dielectric. The electrode finger forms the electrodes. At least a portion of the electrode finger is separated from the first dielectric. A side surface of the first dielectric is formed on the same plane as a side surface of the electrode finger. A second dielectric is formed to cover the electrodes. A dielectric constant of the first dielectric is greater than the dielectric constant of the second dielectric.
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