Title:
LADDER-TYPE FILTER
Document Type and Number:
WIPO Patent Application WO/2022/224740
Kind Code:
A1
Abstract:
Provided is a ladder-type filter capable of enhancing frequency-temperature characteristics. A ladder-type filter 1 of the present invention is provided with: a piezoelectric substrate 2; series arm resonators S1-S5 configured in the piezoelectric substrate 2; parallel arm resonators P1-P4 configured in the piezoelectric substrate 2; an inductance compensation line 5 provided on the piezoelectric substrate 2 and having a first surface 5a and a second surface that oppose each other and a side surface 5c connected to the first surface 5a and the second surface, the second surface of the first surface 5a and the second surface being positioned on the piezoelectric substrate 2 side; and, a coating film 6 (first coating film) for covering at least a part of the first surface 5a and at least a part of the side surface 5c of the inductance compensation line 5. The inductance compensation line 5 is connected to a portion connected in parallel to the series arm resonators and/or a portion connected in series to the parallel arm resonators. The thermal expansion coefficient of the coating film 6 is a negative value.
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Inventors:
OSADA JUNJI (JP)
Application Number:
PCT/JP2022/015446
Publication Date:
October 27, 2022
Filing Date:
March 29, 2022
Export Citation:
Assignee:
MURATA MANUFACTURING CO (JP)
International Classes:
H03H9/145; H03H9/64
Foreign References:
| JPH1117486A | 1999-01-22 | |||
| JP2017523645A | 2017-08-17 | |||
| JPH09167937A | 1997-06-24 |
Attorney, Agent or Firm:
OSAKA FRONT (JP)
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