Patent ID: 6985048

Claim:
A surface acoustic wave apparatus comprising: a longitudinally-coupled-resonator-type surface acoustic wave filter in which an odd number of at least three interdigital transducers are provided on a piezoelectric substrate in a direction in which surface acoustic waves propagate, one interdigital electrode of an interdigital transducer of said at least three interdigital transducers that is disposed at the approximate center of the at least three interdigital transducers is divided into two parts along the propagation direction of title surface acoustic waves and the two parts are connected to balanced signal terminals, and two interdigital transducers of the at least three interdigital transducers that are adjacent to the interdigital transducer disposed at the approximate center are arranged to be inverted with respect to each other and are connected to an unbalanced signal terminal to have a balanced-to-unbalanced conversion function; wherein an outermost electrode finger of the interdigital transducer disposed at the approximate center is a floating electrode or a grounded electrode, and wiring is arranged asymmetrically such that one of the balanced signal terminals that is closer to one of the two interdigital transducers adjacent to the interdigital transducer disposed at the approximate center and of which an outermost electrode finger adjacent to the interdigital transducer disposed at the approximate center is grounded, has a relatively larger capacitance than another of the balanced terminals.