WIDEBAND SURFACE WAVE FILTER

摘要

In a longitudinally coupled multi-mode surface acoustic wave filter, for the purpose of setting a stop band width of reflectors to a proper width according to a required filter, since a line occupation rate of the reflectors has been made smaller than a line occupation rate of an IDT electrode, and respective periods of the reflector and the IDT electrode are set properly such that the stop band width of the reflector and the band width of the longitudinally coupled multi-mode surface acoustic wave filter have been approximately equal to each other, means for broadening the band of the longitudinally coupled multi-mode SAW filter can be obtained for a broad-band RF filter of a portable telephone used in a new system. <IMAGE>