Elastic wave filter, demultiplexer, and communication apparatus

An elastic wave filter comprising:

• at least one series resonator comprising a first IDT electrode;
• and
• at least one parallel resonator comprising a second IDT electrode,
• wherein the at least one series resonator and the one parallel resonator comprise a common piezoelectric film,
• the first IDT electrode comprises:
• a first bus bar and a second bus bar facing each other in a direction intersecting a propagation direction of an elastic wave propagating through the piezoelectric film;
• a plurality of first electrode fingers connected to the first bus bar;
• a plurality of second electrode fingers connected to the second bus bar and interleaved with the plurality of first electrode fingers;
• a plurality of first dummy electrode fingers connected to the first bus bar and facing tips of the plurality of second electrode fingers, respectively;
• and
• a plurality of second dummy electrode fingers connected to the second bus bar and facing tips of the plurality of first electrode fingers, respectively,
• a direction in which the tips of the plurality of first electrode fingers are connected and a direction in which the tips of the plurality of second electrode fingers are connected are inclined with respect to the propagation direction,
• the second IDT electrode comprises:
• a third bus bar and a fourth bus bar facing each other in the direction intersecting the propagation direction;
• a plurality of third electrode fingers connected to the third bus bar;
• a plurality of fourth electrode fingers connected to the fourth bus bar and interleaved with the plurality of third electrode fingers;
• a plurality of third dummy electrode fingers connected to the third bus bar and facing tips of the plurality of fourth electrode fingers, respectively;
• and
• a plurality of fourth dummy electrode fingers connected to the fourth bus bar and facing tips of the plurality of third electrode fingers, respectively,
• a direction in which the tips of the plurality of third electrode fingers are connected and a direction in which the tips of the plurality of fourth electrode fingers are connected are inclined with respect to the propagation direction,
• in the at least one series resonator,
• a duty of the first dummy electrode fingers and a duty of the second dummy electrode fingers are greater than a duty of the first electrode fingers and a duty of the second electrode fingers in at least a part of a first intersection region where the first electrode fingers and the second electrode fingers intersect with each other,
• a duty at a base portion of the first electrode fingers and a duty at a base portion of the second electrode fingers are greater than the duty of the first electrode fingers and the duty of the second electrode fingers in at least a part of the first intersection region, and
• in at least one of the at least one parallel resonator,
• a duty of the third dummy electrode fingers and a duty of the fourth dummy electrode fingers are within a range of ±0.08 with respect to a duty of the third electrode fingers and a duty of the fourth electrode fingers in at least a part of a second intersection region where the third electrode fingers and the fourth electrode fingers intersect with each other, and
• a duty at a base portion of the third electrode fingers and a duty at a base portion of the fourth electrode fingers are within a range of ±0.08 with respect to the duty of the third electrode fingers and the duty of the fourth electrode fingers in at least a part of the second intersection region.