| 摘要 |
PROBLEM TO BE SOLVED: To make a waveform of a pass characteristic of the surface acoustic wave filter symmetrical, to reduce effectively out-band spurious radiation and to obtain a suitable characteristic in the case of designing the surface acoustic wave filter with a steep frequency characteristic. SOLUTION: A total sum of electrode fingers per 1λ, that is, a propagation wavelength of a basic surface acoustic wave is selected the same for an input side transducer 2 and an output side transducer 4, that is, for a unidirectional transducer and a two-way transducer. Thus, the propagation speed of a surface acoustic wave stimulated by the input side transducer 2 is in matching with the propagation speed of a surface acoustic wave stimulated by the output side transducer 4, then a center frequency of the surface acoustic wave stimulated by the input side transducer 2 is in matching with a center frequency of the surface acoustic wave stimulated by the output side transducer 4.
|
