JPS5462756A - Comb line filter using elastic surface wave filter - Google Patents

Abstract

PURPOSE::To obtain a miniaturized comb line filter without characteristic deterioration by arranging the lst and 2nd output converters on an elastic surface wave propagation path at the same side as an input converter and by mixing electric output signals. CONSTITUTION:On piezoelectric substrate 3, output converters 4 and 5 are arranged at the same side as input converter 2. As a result, it can be prevented that a conductor for the input converter and conductor for the output converter intersect each other, and the electric direct coupling between the input and output is reduced, so the no deterioration in characteristic will occur and shielding will be simplified. Further, since the minimum interval between converters is (a)+(b), its size becomes smaller than a conventional one and the chip size also becomes smaller, so that its cost will be reduced. Electric signal energy extracted by output converters 4 and 5 is much smaller than elastic surface wave energy proparating through substrate 3, so that there will be nor problem even if converter 4 is provided onto the proparation path from input converter 2 to converter 5.