| 摘要 |
PROBLEM TO BE SOLVED: To provide a ladder type filter that reduces ripples at a pass band so as to extend the pass band even when a difference between a serial resonance frequency and a parallel resonance frequency of each resonator cannot be increased. SOLUTION: The ladder type filter is provided with a 1st resonator 3 or more that has a 1st series resonance frequency and a 1st parallel resonance frequency higher than the 1st series resonance frequency and is placed on a series arm and with a 2nd resonator 4 or more that has a 2nd series resonance frequency and a 2nd parallel resonance frequency lower than the 1st parallel resonance frequency and is placed on a parallel arm. A 1st inductive element 5 is connected in parallel with the 1st resonator 3 and a 2nd inductive element 6 is inserted in series with the 2nd resonator 4.
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