| 摘要 |
PROBLEM TO BE SOLVED: To smooth an input impedance characteristic of a filter configuring a duplexer, suppress the generation of a ripple in a pass band of an opposite filter and deterioration in characteristics thereof, and reduce an insertion loss. SOLUTION: In the duplexer including two band pass filters F1, F2 having different center frequencies which are connected to a common terminal C in parallel, the low band side filter F2 is provided with a one terminal pair series arm SAW resonator on the first part of the common terminal, the pitch of a reflector in the one terminal pair series SAW resonator is made larger (or smaller) than the pitch of an IDT, and thus, spurious generated at the stop band end position of the high frequency side of the reflector is positioned at a frequency region other than the pass band of the high-frequency side filter. COPYRIGHT: (C)2006,JPO&NCIPI
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