Title:
BALANCED SURFACE ACOUSTIC WAVE FILTER
Document Type and Number:
WIPO Patent Application WO/2006/087875
Kind Code:
A1
Abstract:
A balanced surface acoustic wave filter device having a balance-unbalance converting function and a reduced insertion loss in the passband. The balanced surface acoustic wave filter device (1) is constituted as follows. A first and second surface acoustic wave filter sections (6, 7) parallel connected to an unbalance terminal (3) are connected to first and second balance terminals respectively, so structured that the phase at first balance terminal (4) is different by 180 degrees from that at the second balance terminal (5), and are longitudinally-coupled resonator surface acoustic filter sections having IDTs arranged in the direction of propagation of the surface acoustic wave. The number of pairs of electrode fingers of the second surface acoustic wave filter section (7) where the polarities of the adjacent fingers of the adjacent parts of the IDTs in the direction of propagation of the surface acoustic wave are different is larger than the number of pairs of electrode fingers of the first surface acoustic wave filter section (6) where the polarities of the adjacent fingers of the adjacent parts of the IDTs are the same.
Inventors:
YATA MASARU (JP)
Application Number:
PCT/JP2005/024036
Publication Date:
August 24, 2006
Filing Date:
December 28, 2005
Export Citation:
Assignee:
MURATA MANUFACTURING CO (JP)
YATA MASARU (JP)
YATA MASARU (JP)
International Classes:
H03H9/145; H01L41/22; H01L41/29; H03H9/64
Foreign References:
| JP2003273707A | 2003-09-26 | |||
| JPH07307625A | 1995-11-21 | |||
| JP2004080260A | 2004-03-11 | |||
| JPH01212015A | 1989-08-25 | |||
| JP2004159262A | 2004-06-03 |
Other References:
See also references of EP 1852973A4
Attorney, Agent or Firm:
Miyazaki, Chikara (5-4 Tanimachi 1-chome, Chuo-k, Osaka-shi Osaka 12, JP)
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