Acoustic wave resonator, filter, and multiplexer
An acoustic wave resonator includes: a piezoelectric substrate; and an IDT that is located on the piezoelectric substrate and includes comb-shaped electrodes facing each other, each of the comb-shaped electrodes having grating electrode and a bus bar connected to the grating electrodes, a duty ratio of grating electrodes of the comb-shaped electrodes in a center region of an overlap region differing from a duty ratio of grating electrodes of the comb-shaped electrodes in an edge region of the overlap region in an arrangement direction of the grating electrodes, the grating electrodes of each of the comb-shaped electrodes overlapping with the grating electrodes of the other in the overlap region, a grating electrode of a first one of the comb-shaped electrodes in the center region having a different width from a grating electrode of a second one of the comb-shaped electrodes in the center region.
1. An acoustic wave resonator comprising:
a piezoelectric substrate; and
an IDT that is located on the piezoelectric substrate and includes a pair of comb-shaped electrodes facing each other, each of the pair of comb-shaped electrodes having grating electrodes, which excite an acoustic wave, and a bus bar connected to the grating electrodes, the grating electrodes of a first comb-shaped electrode of the pair of comb-shaped electrodes and the grating electrodes of a second comb-shaped electrode of the pair of comb-shaped electrodes are alternately arranged in at least a part of a region of the IDT in a direction in which the grating electrodes are arranged, a duty ratio of grating electrodes of the pair of comb-shaped electrodes in a center region of an overlap region differing from a duty ratio of grating electrodes of the pair of comb-shaped electrodes in an edge region of the overlap region in the at least the part of the region of the IDT, the grating electrodes of each of the pair of comb-shaped electrodes overlapping with the grating electrodes of the other in the overlap region, a width of grating electrodes of the first comb-shaped electrode of the pair of comb-shaped electrodes in the center region differing from a width of the grating electrodes of the second comb-shaped electrode of the pair of comb-shaped electrodes in the center region in the at least the part of the region of the IDT.
2. The acoustic wave resonator according to claim 1 , wherein
the duty ratio of the grating electrodes of the pair of comb-shaped electrodes in the center region is greater than the duty ratio of the grating electrodes of the pair of comb-shaped electrodes in the edge region in the at least the part of the region of the IDT.
3. The acoustic wave resonator according to claim 1 , wherein
a width of grating electrodes of the first comb-shaped electrode in the edge region is approximately equal to a width of grating electrodes of the second comb-shaped electrode in the edge region in the at least the part of the region of the IDT.
4. The acoustic wave resonator according to claim 1 , wherein
a width of the grating electrodes of the first comb-shaped electrode in the edge region differs from a width of the grating electrodes of the second comb-shaped electrode in the edge region in the at least the part of the region of the IDT.
5. The acoustic wave resonator according to claim 1 , wherein
the grating electrodes of the first comb-shaped electrode in the center region is wider than the grating electrodes of the second comb-shaped electrode in the center region in the at least the part of the region of the IDT,
grating electrodes of the first comb-shaped electrode in the edge region is narrower than grating electrodes of the second comb-shaped electrode in the edge region in the at least the part of the region of the IDT,
the grating electrodes of the first comb-shaped electrode in the edge region is narrower than the grating electrodes of the first comb-shaped electrode in the center region in the at least the part of the region of the IDT, and
the grating electrodes of the second comb-shaped electrode in the edge region is wider than the grating electrodes of the second comb-shaped electrode in the center region in the at least the part of the region of the IDT.
6. The acoustic wave resonator according to claim 1 , wherein
a length of the center region in a direction in which the grating electrodes of each of the pair of comb-shaped electrodes extend is greater than a total length of the edge region in the direction in which the grating electrodes of each of the pair of comb-shaped electrodes extend.
7. The acoustic wave resonator according to claim 1 , wherein
an anisotropy coefficient in the center region is positive.
8. The acoustic wave resonator according to claim 7 , wherein
an acoustic velocity of an acoustic wave excited by the grating electrodes of the pair of comb-shaped electrodes in the edge region is lower than an acoustic velocity of an acoustic wave excited by the grating electrodes of the pair of comb-shaped electrodes in the center region.
9. A filter comprising:
an acoustic wave resonator according to claim 1 .
10. A multiplexer comprising:
a filter including the acoustic wave resonator according to claim 1 .
11. An acoustic wave resonator comprising:
a piezoelectric substrate; and
an IDT that is located on the piezoelectric substrate and includes a pair of comb-shaped electrodes facing each other, each of the pair of comb-shaped electrodes having grating electrodes, which excite an acoustic wave, and a bus bar connected to the grating electrodes, a duty ratio of grating electrodes of the pair of comb-shaped electrodes in a center region of an overlap region differing from a duty ratio of grating electrodes of the pair of comb-shaped electrodes in an edge region of the overlap region in at least a part of a region of the IDT in a direction in which the grating electrodes are arranged, the grating electrodes of each of the pair of comb-shaped electrodes overlapping with the grating electrodes of the other in the overlap region, a width of a grating electrode of a first comb-shaped electrode of the pair of comb-shaped electrodes in the center region differing from a width of a grating electrode of a second comb-shaped electrode of the pair of comb-shaped electrodes in the center region,
wherein
the grating electrode of the first comb-shaped electrode in the center region is wider than the grating electrode of the second comb-shaped electrode in the center region,
a grating electrode of the first comb-shaped electrode in the edge region is narrower than a grating electrode of the second comb-shaped electrode in the edge region,
the grating electrode of the first comb-shaped electrode in the edge region is narrower than the grating electrode of the first comb-shaped electrode in the center region, and
the grating electrode of the second comb-shaped electrode in the edge region is wider than the grating electrode of the second comb-shaped electrode in the center region.
12. An acoustic wave resonator comprising:
a piezoelectric substrate; and
an IDT that Is located on the piezoelectric substrate and includes a pair of comb-shaped electrodes facing each other, each of the pair of comb-shaped electrodes having grating electrodes, which excite an acoustic wave, and a bus bar connected to the grating electrodes, a duty ratio of grating electrodes of the pair of comb-shaped electrodes in a center region of an overlap region differing from a duty ratio of grating electrodes of the pair of comb-shaped electrodes in an edge region of the overlap region in at least a part on a region of the IDT in a direction in which the grating electrodes are arranged, the grating electrodes of each of the pair of comb-shaped electrodes overlapping with the grating electrodes of the other in the overlap region, a width of a grating electrode of a first comb-shaped electrode of the pair of comb-shaped electrodes in the center region differing from a width of a grating electrode of a second comb-shaped electrode of the pair of comb-shaped electrodes in the center region,
wherein
the duty ratio of the grating electrodes of the pair of comb-shaped electrodes in the center region is greater than the duty ratio of the grating electrodes of the pair of comb-shaped electrodes in the edge region.
13. The acoustic wave resonator according to claim 12 , wherein
a width of a grating electrode of the first comb-shaped electrode in the edge region is approximately equal to a width of a grating electrode of the second comb-shaped electrode in the edge region.
14. The acoustic wave resonator according to claim 12 , wherein
a width of a grating electrode of the first comb-shaped electrode in the edge region differs from a width of a grating electrode of the second comb-shaped electrode in the edge region.
15. The acoustic wave resonator according to claim 12 , wherein
a length of the center region in a direction in which the grating electrodes of each of the pair of comb-shaped electrodes extend is greater than a total length of the edge region in the direction in which the grating electrodes of each of the pair of comb-shaped electrodes extend.
16. The acoustic wave resonator according to claim 12 , wherein
an anisotropy coefficient in the center region is positive.
17. The acoustic wave resonator according to claim 16 , wherein
an acoustic velocity of an acoustic wave excited by the grating electrodes of the pair of comb-shaped electrodes in the edge region is lower than an acoustic velocity of an acoustic wave excited by the grating electrodes of the pair of comb-shaped electrodes in the center region.
18. A filter comprising:
an acoustic wave resonator according to claim 12 .
19. A multiplexer comprising:
a filter including an acoustic wave resonator according to claim 12 .