Acoustic wave device
An acoustic wave device includes an acoustic wave resonator and a longitudinally coupled acoustic wave resonator filter, in which the longitudinally coupled acoustic wave resonator filter is shorter than the acoustic wave resonator in terms of a length of first and second edge regions that is a dimension along an extending direction of electrode fingers of the first and second edge regions in an IDT electrode.
1. An acoustic wave device comprising:
an acoustic wave resonator on a first piezoelectric substrate and including an IDT electrode; and
a longitudinally coupled acoustic wave resonator filter on a second piezoelectric substrate and including a plurality of IDT electrodes; wherein
the IDT electrode of the acoustic wave resonator and the IDT electrodes of the longitudinally coupled acoustic wave resonator filter each include a plurality of electrode fingers;
the plurality of electrode fingers include an intersecting region in which the electrode fingers are overlapped with each other in an acoustic wave propagation direction;
the intersecting region includes a central region and first and second edge regions on respective outer side portions in an extending direction of the electrode fingers of the central region and have a lower acoustic velocity than the central region;
first and second gap regions are provided, the first and second gap regions being on outer side portions in the extending direction of the electrode fingers of the first and second edge regions and having a higher acoustic velocity than the central region; and
when a dimension along the extending direction of the electrode fingers of the first and second edge regions is a length of the first and second edge regions, the length of the first and second edge regions in the longitudinally coupled acoustic wave resonator filter is shorter than the length of the first and second edge regions in the acoustic wave resonator.
2. The acoustic wave device according to claim 1 , wherein the first piezoelectric substrate and the second piezoelectric substrate are a same piezoelectric substrate.
3. The acoustic wave device according to claim 1 , wherein the second piezoelectric substrate is a piezoelectric substrate different from the first piezoelectric substrate.
4. The acoustic wave device according to claim 1 , wherein a width of the plurality of electrode fingers in the first and second edge regions is larger than a width of the plurality of electrode fingers in the central region.
5. The acoustic wave device according to claim 1 , wherein a mass addition film is provided on the plurality of electrode fingers in the first and second edge regions.
6. The acoustic wave device according to claim 5 , wherein a thickness of the mass addition film in the acoustic wave resonator is the same or substantially the same as a thickness of the mass addition film in the longitudinally coupled acoustic wave resonator filter.
7. The acoustic wave device according to claim 1 , wherein an acceleration film is stacked on the electrode fingers in the central region.
8. The acoustic wave device according to claim 1 , wherein
the first piezoelectric substrate and the second piezoelectric substrate each include a multilayer body in which a high acoustic velocity material layer and a piezoelectric film are stacked in this order; and
an acoustic velocity at which a bulk wave is propagated through the high acoustic velocity material layer is higher than an acoustic velocity at which an acoustic wave is propagated through the piezoelectric film.
9. The acoustic wave device according to claim 8 , wherein
the first piezoelectric substrate and the second piezoelectric substrate each include a low acoustic velocity film between the high acoustic velocity material layer and the piezoelectric film; and
an acoustic velocity at which a bulk wave is propagated through the low acoustic velocity film is lower than an acoustic velocity at which a bulk wave is propagated through the piezoelectric film.
10. The acoustic wave device according to claim 8 , wherein the high acoustic velocity material layer is a support substrate made of a high acoustic velocity material.
11. The acoustic wave device according to claim 8 , wherein
the high acoustic velocity material layer is a high acoustic velocity film made of a high acoustic velocity material; and
the acoustic wave device further includes a support substrate supporting the high acoustic velocity material layer.
12. The acoustic wave device according to claim 2 , wherein a width of the plurality of electrode fingers in the first and second edge regions is larger than a width of the plurality of electrode fingers in the central region.
13. The acoustic wave device according to claim 3 , wherein a width of the plurality of electrode fingers in the first and second edge regions is larger than a width of the plurality of electrode fingers in the central region.
14. The acoustic wave device according to claim 2 , wherein a mass addition film is provided on the plurality of electrode fingers in the first and second edge regions.
15. The acoustic wave device according to claim 14 , wherein a thickness of the mass addition film in the acoustic wave resonator is the same or substantially the same as a thickness of the mass addition film in the longitudinally coupled acoustic wave resonator filter.
16. The acoustic wave device according to claim 3 , wherein a mass addition film is provided on the plurality of electrode fingers in the first and second edge regions.
17. The acoustic wave device according to claim 16 , wherein a thickness of the mass addition film in the acoustic wave resonator is the same or substantially the same as a thickness of the mass addition film in the longitudinally coupled acoustic wave resonator filter.
18. The acoustic wave device according to claim 2 , wherein an acceleration film is stacked on the electrode fingers in the central region.
19. The acoustic wave device according to claim 3 , wherein an acceleration film is stacked on the electrode fingers in the central region.