Patent ID: 11863159
Assignee: MURATA MANUFACTURING CO., LTD.
Field: Basic communication processes (Electrical engineering)
Classification: CPC H | IPC H

Claim 18:
19. The acoustic wave filter according to claim 1, further comprising:
a third series-arm resonator disposed on the path, the first series-arm resonator and the third series-arm resonator being connected in series; wherein
the third series-arm resonator has a lower anti-resonant frequency than the second series-arm resonator;
the third series-arm resonator includes an IDT electrode including a pair of comb teeth-shaped electrodes provided on a substrate including a piezoelectric layer;
electrodes of the pair of comb teeth-shaped electrodes of the third series-arm resonator each include electrode fingers and a busbar electrode, the electrode fingers extending in the direction orthogonal or substantially orthogonal to the propagation direction of the acoustic wave, the busbar electrode connecting first ends of the electrode fingers to each other;
a direction in which second ends of the electrode fingers are aligned with each other crosses the propagation direction of the acoustic wave;
the electrode fingers of the IDT electrode of the third series-arm resonator each include an electrode-finger central portion and a wide portion located at the second end and being wider than the electrode-finger central portion; and
a length of the wide portion of each of the electrode fingers in the third series-arm resonator in the direction in which the electrode fingers extend is greater than the length of the wide portion of each of the electrode fingers in the second series-arm resonator in the direction in which the electrode fingers extend.