Patent ID: 11962287
Assignee: MURATA MANUFACTURING CO., LTD.
Field: Basic communication processes (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. An acoustic wave filter comprising:
a first input/output terminal and a second input/output terminal;
a plurality of series arm resonators along a path connecting the first input/output terminal and the second input/output terminal; and
one or more parallel arm resonators each between a node in the path and ground; wherein
each of the plurality of series arm resonators and the one or more parallel arm resonators includes an acoustic wave resonator that includes an interdigital transducer (IDT) electrode on a substrate having piezoelectricity;
the IDT electrode includes a pair of comb-shaped electrodes each including a plurality of electrode fingers and a busbar electrode, the plurality of electrode fingers being in parallel or substantially in parallel to one another and extending in a direction that crosses an acoustic wave propagation direction, the busbar electrode connecting one-end portions of the electrode fingers of the plurality of electrode fingers;
of the plurality of electrode fingers, an electrode finger not connected to either one of the busbar electrodes of the pair of comb-shaped electrodes is a floating withdrawal electrode; and
of the plurality of electrode fingers, an electrode finger connected to a same busbar electrode to which electrode fingers on both sides thereof are connected is a polarity-reversing withdrawal electrode;
of the plurality of series arm resonators, a first series arm resonator having a lowest anti-resonant frequency includes an IDT electrode including the floating withdrawal electrode; and
of the plurality of series arm resonators, at least one series arm resonator other than the first series arm resonator includes an IDT electrode including the polarity-reversing withdrawal electrode.