Surface-acoustic-wave device and communication device having the surface-acoustic-wave device

摘要

A surface-acoustic-wave device having an unbalanced-to-balanced conversion function, which is capable of improving balanced characteristics, is provided. The surface-acoustic-wave device includes a first resonator filter (1) and a second resonator filter (2), each having a plurality of interdigital transducers (11-13/21-23) formed along the propagation direction of a surface-acoustic wave. The surface-acoustic-wave device has an unbalanced-to-balanced conversion function as a result of the phase of the second resonator filter (2) being reversed by 180° with respect to that of the first resonator filter (1). The surface-acoustic-wave device further includes a first resonator (3) connected in series to an unbalanced signal terminal side of the first resonator filter (1), and a second resonator (4) connected in series to an unbalanced signal terminal side of the second resonator filter (2). The first resonator (3) and the second resonator (4) are formed with different design parameters.