| 摘要 |
PROBLEM TO BE SOLVED: To improve the steepness of filter characteristics and to prevent the enlargement of a device by adding parallel capacity in a surface acoustic wave device provided with a multiple mode filter. SOLUTION: In this surface acoustic wave device provided with the multiple mode filter for which at least two surface acoustic wave resonators 20a and 20b are adjacently arranged, by the parallel capacity formed by the input bus- bar 24a and output bus-bar 24b of interdigital type transformers 21a and 21b provided in the surface acoustic wave resonators, the steepness of the filter characteristics is improved. In this case, in the interdigital type transformer, at the time of defining an electrode finger pitch asλdefining the distance of the input bus-bar 24a and the output bus-bar 24b as D and defining the average of the width La of the input bus-bar and the width Lb of the output bus-bar as Lab, (Lab/λ)/(D/λ)<2> =(Lab.λ)/D<2> =0.025-0.125 is satisfied.
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