Surface acoustic wave device

A surface acoustic wave device comprising:

• a first surface acoustic wave filter element including a first piezoelectric substrate, and at least two interdigital transducers arranged along the surface acoustic wave propagation direction on the first piezoelectric substrate;
• a second surface acoustic wave filter element including a second piezoelectric substrate, and at least two interdigital transducers arranged along the surface acoustic wave propagation direction on the second piezoelectric substrate, the second surface acoustic wave filter element having a transmission phase characteristic that is different by about 180° from that of the first surface acoustic wave filter element;
• the first and second surface acoustic wave filter elements each having an input terminal and an output terminal, selected ones of the input terminals and the output terminals of the first and second surface acoustic wave filter elements being commonly connected to each other at a common connection point;
• an unbalanced signal terminal being connected to the common connection point;
• the other terminals of the input terminals and the output terminals of the first and second surface acoustic wave filter elements defining first and second balanced signal terminals, respectively;
• and
• a delay line provided between the common connection point and the first surface acoustic wave filter element.

A surface acoustic wave device comprising:

• a first surface acoustic wave filter element including a first piezoelectric substrate, and at least two interdigital transducers arranged along the surface acoustic wave propagation direction on the first piezoelectric substrate;
• a second surface acoustic wave filter element including a second piezoelectric substrate, and at least two interdigital transducers arranged along the surface acoustic wave propagation direction on the second piezoelectric substrate, the second surface acoustic wave filter element having a transmission phase characteristic that is different by about 180° from that of the first surface acoustic wave filter element;
• the first and second surface acoustic wave filter elements each having an input terminal and an output terminal, selected ones of the input terminals and the output terminals of the first and second surface acoustic wave filter elements being commonly connected to each other at a common connection point;
• an unbalanced signal terminal being connected to the common connection point;
• and
• the other terminals of the input terminals and the output terminals of the first and second surface acoustic wave filter elements defining first and second balanced signal terminals, respectively,
• wherein a first length of the signal line between the common connection point and the interdigital transducers of the first surface acoustic wave filter element electrically connected to the common connection point is different from a second length of the signal line between the common connection point and the interdigital transducers of the second surface acoustic wave filter element electrically connected to the common connection point.