| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface acoustic wave filter in which the flatness of an insertion loss in a pass band can be enhanced and the fluctuation of the insertion loss in the pass band can be reduced even when the filter characteristics are changed due to temperature change. SOLUTION: The surface acoustic wave filter 1 is provided with a longitudinally-coupled resonator mode SAW filter portion 101 having at least two interdigital transducers (IDTs) disposed on a piezoelectric substrate 2 and with at least one SAW resonator 104 electrically connected in parallel with the SAW filter portion 101 such that the at least one SAW resonator 104 is disposed between an input terminal or an output terminal and the SAW filter portion 101. The resonance point of the SAW resonator is disposed in the pass band of the SAW filter portion 101.
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