Surface acoustic wave device and communication device

A communication device, comprising

• at least one of a reception circuit and a transmission circuit which has a surface acoustic wave device,
• wherein the surface acoustic wave device comprises
• a piezoelectric substrate comprising a first region, a second region and a third region, the second and third regions arranged adjoining the both sides of the first region;
• a first surface acoustic wave element in the second region on the piezoelectric substrate, in which first, second and third IDT electrodes are arranged along a direction of propagation of a surface acoustic wave propagated on the piezoelectric substrate, the second IDT electrode arranged at the center among the first, second and third IDT electrodes comprising first split bus bar electrodes arranged on the first region side on the piezoelectric substrate and split into two and a non-split bus bar electrode arranged on the second region side on the piezoelectric substrate and connected to a reference potential electrode,
• a second surface acoustic wave element in the third region on the piezoelectric substrate, in which fourth, fifth and sixth IDT electrodes are arranged along the direction of propagation of the surface acoustic wave propagated on the piezoelectric substrate, the fifth IDT electrode arranged at the center among the fourth, fifth and sixth IDT electrodes comprising second split bus bar electrodes arranged on the first region side so as to adjoin the first split bus bar electrodes and a non-split bus bar electrode arranged on the third region side on the piezoelectric substrate;
• balanced signal lines arranged in the first region and connecting the first split bus bar electrodes and the second split bus bar electrodes so as to cascade-connect the first and second surface acoustic wave elements;
• a first unbalanced signal terminal connected to the second and third IDT electrodes of the first surface acoustic wave element and arranged in the second region;
• and
• a second unbalanced signal terminal connected to the fourth and sixth IDT electrodes of the second surface acoustic wave element and arranged in the third region;
• and
• first and second reflector electrodes disposed on both sides of the first, second and third IDT electrodes arranged in the direction of propagation,
• wherein the non-split bus bar electrode of the second IDT electrode of the first surface acoustic wave element and the first and second reflector electrodes are connected to the reference potential electrode via a lead out line for a reference potential, and a signal lead out line connecting the first and third IDT electrodes to the first unbalanced signal terminal crosses the lead out line for a reference potential with an insulator interposed therebetween.

A surface acoustic wave device, comprising:

• a piezoelectric substrate comprising a first region, a second region and a third region, the second and third regions arranged adjoining both sides of the first region;
• a first surface acoustic wave element in the second region on the piezoelectric substrate, in which first, second and third IDT electrodes are sequentially arranged along a direction of propagation of the surface acoustic wave propagated on the piezoelectric substrate, the second IDT electrode arranged at the center among the first, second and third IDT electrodes comprising first split bus bar electrodes arranged on the first region side on the piezoelectric substrate and split into two and a non-split bus bar electrode arranged in the second region on the piezoelectric substrate and connected to a reference potential electrode arranged in the second region;
• a second surface acoustic wave element in the third region on the piezoelectric substrate, in which fourth, fifth and sixth IDT electrodes are sequentially arranged along the direction of propagation of the surface acoustic wave propagated on the piezoelectric substrate, the fifth IDT electrode arranged at the center among the fourth, fifth and sixth IDT electrodes comprising second split bus bar electrodes arranged on the first region side so as to adjoin the first split bus bar electrodes and a non-split bus bar electrode arranged in the third region on the piezoelectric substrate;
• balanced signal lines arranged in the first region and connecting the first split bus bar electrodes and the second split bus bar electrodes so as to make cascade connection between the first and second surface acoustic wave elements;
• a first unbalanced signal terminal connected to the first and third IDT electrodes of the first surface acoustic wave element and arranged in the second region;
• a second unbalanced signal terminal connected to the fourth and sixth IDT electrodes of the second surface acoustic wave element and arranged in the third region;
• and
• first and second reflector electrodes disposed on both sides of the first, second and third IDT electrodes arranged in the direction of propagation,
• wherein the non-split bus bar electrode of the second IDT electrode of the first surface acoustic wave element and the first and second reflector electrodes are connected to the reference potential electrode via a lead out line for a reference potential, and a signal lead out line connecting the first and third IDT electrodes to the first unbalanced signal terminal crosses the lead out line for a reference potential with an insulator interposed therebetween.