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Patent Searching and Data


Title:
VARIABLE-FREQUENCY FILTER
Document Type and Number:
WIPO Patent Application WO/2015/045882
Kind Code:
A1
Abstract:
This variable-frequency filter (10) is provided with a filter unit (20) and a matching circuit (31, 32). The filter unit (20) is provided with a variable-frequency resonant circuit (21, 22) that has a piezoelectric resonator. The matching circuit (31, 32) has a circuit architecture whereby the real component of the impedance of said matching circuit (31, 32) increases as the frequency increases. For example, the matching circuit (31, 32) could have an L-shaped circuit architecture using an inductor and a capacitor, with a reactance element shunt-connected to the filter-unit (20) side. Since the filter unit (20) has a piezoelectric resonator, the real component of the impedance of the filter unit (20) increases as the passband is shifted towards the high-frequency side, but since the real component of the impedance of the matching circuit (31, 32) also increases as the frequency increases, impedance matching is achieved.

Inventors:
KANDO HAJIME (JP)
TANI MASAKAZU (JP)
Application Number:
PCT/JP2014/074032
Publication Date:
April 02, 2015
Filing Date:
September 11, 2014
Export Citation:
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Assignee:
MURATA MANUFACTURING CO (JP)
International Classes:
H03H9/64; H03H7/12; H03H7/38
Domestic Patent References:
WO2011093449A12011-08-04
WO2012079038A22012-06-14
Foreign References:
JPH077366A1995-01-10
JP2006135447A2006-05-25
JP2012501563A2012-01-19
Attorney, Agent or Firm:
Kaede Patent Attorneys' Office (JP)
Patent business corporation Kaede Patent Attorneys' Office (JP)
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