ELASTIC SURFACE WAVE FILTER

摘要

PURPOSE:To ensure the sufficient compensation for the diffraction effect of the elastic surface wave and thus to obtain the excellent filter properties by installing the 3rd electrode similar to transducer TRD with the cross-width weight between such TRD and the input/output TRD of the uniform cross width. CONSTITUTION:Input TRD11 with the cross-width weight plus its opposing output TRD12 of the uniform cross width are provided on the piezoelectric substrate. Then power source 13 is connected to TRD11 via input resistance 14; while load resistance 15 is connected to TRD12 each. And 3rd electrode 16 which is the similar type to TRD11 is installed to the surface wave propagation path between TRD11 and 12. As TRD11 features the split-type, electrode 16 also uses the split-type. While TRD12 uses the solid-type. In the case of the split-type electrode, the mutual reflection is negated at the electrode edge by arranging 1/8-input electrode width 21 and 5/8-input electrode width 22 alternately. Thus the diffraction effect can be compensated to obtain the excellent filter properties.