Surface acoustic wave filter device having first through third surface acoustic wave filter elements

A surface acoustic wave filter device comprising:

• a piezoelectric substrate having an input side and an output side;
• and
• first, second and third surface acoustic wave filter elements disposed on said piezoelectric substrate;
• wherein
• the first surface acoustic wave filter element includes a first IDT arranged along a surface acoustic wave propagation direction and also includes second and third IDTs disposed on respective opposite sides, in the surface acoustic wave propagation direction, of the first IDT;
• said second and third surface acoustic wave filter elements each include a plurality of IDTs disposed along the surface acoustic wave propagation direction;
• said second and third surface acoustic wave filter elements are arranged such that they are substantially equal in transmission amplitude characteristic within a band but different in transmission phase characteristic by about 180°;
• and
• the second IDT of the first surface acoustic wave filter element is connected to the second surface acoustic wave filter element, and the third IDT of the first surface acoustic wave filter element is connected to an IDT of the third surface acoustic wave filter element;
• wherein
• the input side includes only the first surface acoustic wave filter, and the output side includes the second and third surface acoustic wave filters.