Surface acoustic wave device with IDT electrodes having different electrode finger pitches and communication apparatus using same

A surface acoustic wave device, comprising:

• a piezoelectric substrate;
• and
• a plurality of surface acoustic wave elements on the piezoelectric substrate, wherein
• each surface acoustic wave element comprises N number of IDT electrodes having a serially divided structure and arranged along a propagation direction of a surface acoustic wave, N being a whole number of 3 or more,
• each of the IDT electrodes comprises
• floating electrode comprising
• a center bus bar,
• a plurality of first forting electrode fingers having first end connected to one long side of the center bus bar and arranged at intervals from each other, and
• a plurality of second floating electrode fingers having first ends connected to the other long side of the center bus bar and arranged at intervals from each other,
• a first electrode with a plurality of electrode fingers between the plurality of first floating electrode fingers, and
• a second electrode with a plurality of electrode fingers between the plurality of second floating electrode fingers,
• when any three continuously and sequentially arranged IDT electrodes among the plurality of IDT electrodes are a first, second, and third IDT electrodes in the order of arrangement, and
• when dividing each surface acoustic wave element into a first region and a second region using a center line of the center bus bar as the boundary, and the first region comprises the first floating electrode fingers and first electrode and the second region comprises the second floating electrode fingers and second electrode are arranged,
• a first electrode finger pitch P1 at the boundary between the first IDT electrode and the second IDT electrode in the first region and a second electrode finger pitch P2 at the boundary between the second IDT electrode and the third IDT electrode in the first region are equal, the first and second electrode finger pitches P1 and P2 are the smallest among all electrode finger pitches of the N number of IDT electrodes in the first region, and
• each of the IDT electrodes comprises a third electrode finger pitch P3 larger than the first and second electrode finger pitches P1 and P2 in the first region,
• wherein in the IDT electrodes, electrode finger pitch from one end to the other end in the first region and electrode finger pitch from one end to the other end in the second region changes differently.