Title:
PIEZOELECTRIC CERAMIC FILTER CIRCUIT AND PIEZOELECTRIC CERAMIC FILTER
Document Type and Number:
WIPO Patent Application WO/1994/001931
Kind Code:
A1
Abstract:
A plurality of piezoelectric ceramic filters have center frequencies which differ from each other, and are cascaded to each other. Letting the absolute value of the frequency difference dF0 of the center frequency be |dF0|, and the passband width be BW3 when the insertion loss is below 3db, the piezoelectric ceramic filter satisfies the following condition, 0 < |dF0| / BW3 < 0.8. Thus, it is possible to achieve the reduction of the insertion loss and the improvement of the group delay characteristics at the same time.
Inventors:
KATOH IKUO (JP)
MOMIYAMA TSUYOSHI (JP)
MOMIYAMA TSUYOSHI (JP)
Application Number:
PCT/JP1993/000922
Publication Date:
January 20, 1994
Filing Date:
July 05, 1993
Export Citation:
Assignee:
TDK CORP (JP)
KATOH IKUO (JP)
MOMIYAMA TSUYOSHI (JP)
KATOH IKUO (JP)
MOMIYAMA TSUYOSHI (JP)
International Classes:
H03H9/05; H03H9/10; H03H9/56; (IPC1-7): H03H9/56
Foreign References:
| JPS548440A | 1979-01-22 | |||
| JPS5710092Y2 | 1982-02-26 | |||
| JPS5518190A | 1980-02-08 | |||
| JPS5624820A | 1981-03-10 | |||
| JPS6175629U | 1986-05-21 | |||
| JPS4962055A | 1974-06-15 |
Other References:
See also references of EP 0650255A4
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