| 摘要 |
A first and a second longitudinally coupled resonator-type surface acoustic wave filter are disposed on a piezoelectric substrate. One end of a first IDT arranged at the middle of the first longitudinally coupled resonator-type surface acoustic wave filter is connected to a first unbalanced terminal, and one end of a first IDT arranged at the middle of the second longitudinally coupled resonator-type surface acoustic wave filter is connected to a second unbalanced terminal. Signal terminals of second IDTs of the first and the second longitudinally coupled resonator-type surface acoustic wave filter are connected to each other with a first signal line. Third IDTs are connected to each other with a second signal line. A capacitor is connected between the first and the second signal line. The above arrangement provides a cascaded longitudinally coupled resonator-type surface acoustic wave filter device including an inter-stage capacitor is miniaturized.
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