| 摘要 |
PURPOSE:To increase the band width of a surface acoustic wave filter by setting side by side two 2-port type surface acoustic wave resonators having slightly different resonance frequencies with their input sides connected in parallel and output sides connected in adverse phases with each other. CONSTITUTION:The 1st and 2nd 2-port surface acoustic wave resonators are formed on the same piezoelectric substrate with their pass characteristics set with slight difference from each other. The input inter-digital converters 11 and 21 of the 1st and 2nd resonators are connected in parallel to the input terminal. While the output inter-digital converters 12 and 22 of the 1st and 2nd resonators are connected to the output terminal with adverse phases to each other. In such a constitution, a surface acoustic wave resonator filter secures a band width accordant with the pass band widths of both resonators in terms of the pass characteristics.
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