Surface acoustic wave filter and surface acoustic wave duplexer with the same

A surface acoustic wave and filter technology, applied in electrical components, impedance networks, etc., can solve problems such as poor band-pass characteristics of surface acoustic wave filters and form factors
CN1494210AInactive Publication Date: 2004-05-05TAIYO YUDEN KK
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
TAIYO YUDEN KK
Publication Date
2004-05-05
Estimated Expiration
Not applicable · inactive patent

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Abstract

A surface acoustic wave filter includes a series-arm resonators and parallel-arm resonators that are connected in a ladder-like structure, each having an interdigital transducer formed on a piezoelectric substrate, and at least one of the series-arm resonators having a different static capacitance from the other series-arm resonators. In this surface acoustic wave filter, at least one of the series-arm resonators except the series-arm resonator located at the first stage in the ladder-like structure has a lower average resonant frequency than the other series-arm resonators.
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Description

technical field

[0001] The present invention relates generally to surface acoustic wave filters, and more particularly to a surface acoustic wave filter for a high frequency unit of a mobile communication device, the filtering characteristics of which requires a high form factor. The present invention also relates to a surface acoustic wave duplexer (antenna duplexer) having the surface acoustic wave filter. Background technique

[0002] Today, the transmission and reception bands of mobile communication systems are very close to each other, so that the limited frequency band area can be efficiently used. For example, in PCS (Personal Communications Services) in North America, although the passband is at 1.9 GHz, the frequency gap between the transmission band and the reception band is only 20 MHz.

[0003] In order to avoid crosstalk in such a mobile communication system, in an antenna duplexer that separates a transmission signal and a reception signal, the frequency regi...

Claims

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