ANTENNA SHARING DEVICE

摘要

An antenna sharing device is provided with a first elastic wave filter which allows passage of a signal in a first frequency band, and a second elastic wave filter which allows passage of a signal in a second frequency band which is higher than the first frequency band, wherein the first elastic wave filter comprises a ladder type filter including a first series resonator and a second series resonator which has an antiresonant frequency point higher than that of the first series resonator, the first series resonator comprises a first IDT electrode and a first dielectric film which is formed to cover the first IDT electrode and to have a first projection above an electrode finger, the second series resonator comprises a second IDT electrode and a second dielectric film which is formed to cover the IDT electrode and to have a second projection above an electrode finger, and a cross-sectional area of the first projection in the excitation direction of the elastic wave of the first series resonator is larger than a cross-sectional area of the second projection in the excitation direction of the elastic wave of the second series resonator. Thereby, the antenna sharing device can have both steepness in a cross-band, and low loss in a passband.