A SAW device which has a surface acoustic wave filter (SAW filter) configured by IDT (InterDigital Transducer) electrodes arranged along the propagation direction of the SAW is known (for example the patent literature 1). Each IDT electrode has a plurality of electrode fingers which extend orthogonal to the propagation direction of the SAW and are arranged along the propagation direction of the SAW. The pitches of the plurality of electrode fingers (electrode finger pitches) are suitably set in accordance with a frequency of a passband or the like.
As disclosed in the patent literature 1 as well, in such a SAW device, as a means for increasing an amount of out-of-band attenuation at a low frequency side, generally a method of longitudinally connecting (cascade connecting) two SAW filters is employed.
The SAW device which has a plurality of SAW filters which are connected in multiple stages becomes larger in size along with an increase of the number of SAW filters. Further, the patent literature 1 does not allude to the pitch which contributes to an increase of the amount of out-off-band attenuation.
Therefore, a surface acoustic wave device able to increase the amount of out-of-band attenuation with a compact configuration is preferably provided.
USPTO Backgrounds
USPTO Backgrounds