| 摘要 |
A boundary acoustic wave device which can suppress an undesired response due to interdigital capacitive electrode. The boundary acoustic wave device comprises a first medium, a second medium laid on the first medium, and a plurality of electrodes arranged on the boundary between the first and second media, characterized in that a filter and/or a resonator and a capacitor connected electrically with the filter and/or the resonator are constituted of the plurality of electrodes, each of the filter and/or the resonator is constituted using an IDT electrode, the capacitor is formed of an interdigital capacitive electrode, and a relation Vm/?m<Vc/?c is satisfied assuming the period of electrode finger of the IDT is ?m, the sound velocity of a boundary acoustic wave in the IDT is Vm, the period of electrode finger of the interdigital capacitive electrode is ?c, and the lower one of sound velocities of slow transverse waves in the electrode finger normal direction of the interdigital capacitive electrode of the first and second media is Vc. |
