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Surface acoustic wave resonator, combined surface acoustic wave filter and surface acoustic wave filter

A surface acoustic wave and resonator technology, applied in impedance networks, electrical components, etc., can solve the problem of inability to obtain large attenuation, and achieve the effect of reducing the area

Inactive Publication Date: 2005-01-05
MURATA MFG CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the result of this actual connection is that, as mentioned above, the resonant frequency in the series case is far away from the vicinity of the passband, so that a large amount of attenuation cannot be obtained near the passband
That is, according to the conventional method (in which a SAW resonator is connected to a SAW filter), a large amount of attenuation in a region very close to the passband and a good insertion loss in the passband are contradictory

Method used

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  • Surface acoustic wave resonator, combined surface acoustic wave filter and surface acoustic wave filter
  • Surface acoustic wave resonator, combined surface acoustic wave filter and surface acoustic wave filter
  • Surface acoustic wave resonator, combined surface acoustic wave filter and surface acoustic wave filter

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Embodiment Construction

[0067] Hereinafter, a description will be provided of a SAW resonator and a composite SAW filter according to preferred embodiments of the present invention with reference to the accompanying drawings.

[0068] figure 1 is a plan view for explaining the first preferred embodiment of the composite SAW filter according to the present invention.

[0069] In the composite SAW filter of this preferred embodiment, the SAW filter 1 and the SAW filter 2 are preferably provided on a piezoelectric substrate 8 made of 36-degree Y-cut X-propagation direction LiTaO3. The materials for determining the electrodes of the SAW filter 1 and the SAW filter 2 are not particularly limited, but an aluminum material is preferably used.

[0070] The SAW filter 1 is preferably a vertically coupled dual-mode SAW filter having a three-IDT configuration of IDT3, 4a and 4b. Also, it is preferable to arrange the reflectors 5a and 2 on both sides of the area where the IDTs 3, 4a and 4b are arranged along ...

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Abstract

A surface acoustic wave resonator includes a piezoelectric substrate and an interdigital transducer on the piezoelectric substrate. The interdigital transducer includes first and second comb-shaped electrodes having one or more electrode fingers which are interdigitated with each other. When the first comb-shaped electrode is connected to a positive potential, the second comb-shaped electrode is connected to a negative potential, and the electrode finger connected to the positive potential and the electrode finger connected to the negative potential are reversed in at least one pair of the electrode fingers in an area where electrode fingers connected to the positive potential and electrode fingers connected to the negative potential are alternately arranged in the direction of surface-wave propagation.

Description

technical field [0001] The present invention relates to a single-ended type SAW resonator and surface acoustic wave (SAW) filter incorporated in, for example, bandpass filters or other filters used in cellular phones and other communication devices. Background technique [0002] SAW filters are widely used as bandpass filters in cellular phones and other communication devices. In recent communication systems such as portable telephones, the transmission frequency band and the reception frequency band are close to each other. Therefore, the attenuation characteristic near the end of the pass band, that is, the sharpness of the attenuation characteristic is increasingly required. [0003] In order to meet the above needs, a composite SAW filter is disclosed in Japanese Unexamined Patent Publication No. 7-131290. In this composite SAW filter, a first SAW resonator is connected in parallel to one of the input and output side filters of the SAW filter, and the second SAW resona...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03H9/145H03H9/25H03H9/64
CPCH03H9/6436H03H9/14517H03H9/6483H03H9/64
Inventor 藤井裕久高峰裕一
Owner MURATA MFG CO LTD
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