Patent ID: 8704612

Claim:
An antenna sharing device comprising: a first elastic wave filter as a ladder-type filter for passing a signal of a first frequency band, the first elastic wave filter including: a first series resonator including: a first IDT electrode having a plurality of electrode fingers; and a first dielectric film that covers the first IDT electrode and has a first projection above the electrode fingers; and a second series resonator having an antiresonant frequency point higher than that of the first series resonator, the second series resonator including: a second IDT electrode having a plurality of electrode fingers; and a second dielectric film that covers the second IDT electrode and has a second projection above the electrode fingers; and a second elastic wave filter for passing a signal of a second frequency passband that is higher than the first frequency passband, wherein, the first projection in an excitation direction of an elastic wave of the first series resonator has a cross-sectional area larger than a cross-sectional area of the second projection in an excitation direction of an elastic wave of the second series resonator.