| 摘要 |
PROBLEM TO BE SOLVED: To reduce the number of elements for performing impedance matching of a surface acoustic wave filter and to suppress deterioration of group delay characteristic. SOLUTION: This surface acoustic wave filter, provided with a surface acoustic wave(SAW) multimode filter 112 composed of SAW multimode resonators 105 and 109 on which IDT electrodes 102a, 102b, 106a and 106b and reflectors 103a to 104b and 107a to 108b are arranged and a capacitor 111 on a single crystal piezoelectric substrate 101, is used. Then, the input/output impedance of the filter 112 is changed by the capacity component and internal resistance component of the capacitor 111, the number of elements for performing impedance matching with an external circuit, and also the impedance change by a matching circuit is made small to suppress the deterioration of group delay deviation.
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