Surface acoustic wave filter

A surface acoustic wave filter significantly improves attenuation in the stopband by using a spurious component to improve the filter characteristics. The filter includes a surface acoustic wave substrate (22) and a series resonator (24,26) having a resonant frequency and an antiresonant frequency. The series resonator is electrically disposed between an input terminal (IN) and an output terminal (OUT) in series so as to define a series arm. The filter also includes at least one parallel resonator (23,25,27) having a resonant frequency, and having an antiresonant frequency which is substantially identical to the resonant frequency of the series resonator. The at least one parallel resonator (23,25,27) is electrically disposed between the series arm and a ground terminal so as to define a first parallel arm. The series arm and the parallel arm define a ladder circuit such that the surface acoustic wave filter has a predetermined pass band. The first parallel resonator (23,25,27) has a spurious component at a frequency located between the resonant frequency of the first parallel resonator and a low end of the passband of the surface acoustic wave filter or at a frequency located between the antiresonant frequency of the series resonator and a high end of the passband of the surface acoustic wave filter.