| 摘要 |
A surface acoustic wave filter includes, on a piezoelectric substrate, longitudinally coupled resonator type surface acoustic wave filter sections, including interdigital transducers, each having a narrow-pitched electrode finger portion in an area where interdigital transducers are adjacent to each other, first surface acoustic wave resonators, between the surface acoustic wave filter sections and an input terminal, and second surface acoustic wave resonators between the surface acoustic wave filter sections and output terminals. The resonance point of the surface acoustic wave resonators falls within the passband of the surface acoustic wave filter sections, and the antiresonance point of the surface acoustic wave resonators is in the vicinity of the high frequency side of the passband.
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