SURFACE ACOUSTIC WAVE FILTER - Matsushita Electric Industrial Co., Ltd

Title:

SURFACE ACOUSTIC WAVE FILTER

Document Type and Number:

Japanese Patent JP3424971

Kind Code:

B2

Abstract:

PURPOSE: To easily perform the fine adjustment of out of band attenuation amount by performing a cascade connection of three-electrode type surface acoustic wave vertical coupling filters on the same substrate and substantially performing a complex conjugate for the impedance where each filler is viewed from a connection point in the frequency within the passing band of the filter.
CONSTITUTION: A filter composed of a surface acoustic wave filter composed by connecting surface wave resonators serially 101 and in parallel 102 and a reflector 105 where an input interdigital electrode 103 and an output interdigital electrode 1 04 are formed at the both ends of an input/output electrode is provided. At this stage, these filters are connected in cascade on the same substrate and the impedance where each filter is viewed from a connection point becomes a complex conjugate in the frequency within the passing bands of the filters. As a result, the worse rise in a lower frequency area than in the passing band can be compensated by a three-electrode type filter. The ripple generated in a high frequency area is compensated by a resonator type filter and the input/output impedance can be approached to 50Ω.

Inventors:

Yutaka Taguchi
Kazuo Eda
Keiji Ohnishi
Shunichi Seki

Application Number:

JP447194A

Publication Date:

July 07, 2003

Filing Date:

January 20, 1994

Export Citation:

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