Elastic surface-wave device

A surface acoustic wave and range technology, applied in the direction of impedance network, electrical components, etc., can solve the problems of inaccessibility, large reflection coefficient, etc.

Active Publication Date: 2005-05-04
MURATA MFG CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, if the metallization ratio of the interdigital electrodes is set to 0.5, a large reflection coefficient cannot be obtained

Method used

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  • Elastic surface-wave device
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Embodiment Construction

[0031] Hereinafter, the present invention will be clarified by describing specific examples of the surface acoustic wave device of the present invention with reference to the drawings.

[0032] figure 1 It is a schematic perspective view of a surface acoustic wave device according to an embodiment of the present invention, and FIG. 2 is a schematic partial cutaway front sectional view.

[0033] The surface acoustic wave device 1 has an ST-cut crystal substrate 2 . The crystal substrate 2 is a crystal substrate with an ST-cut 90° X conveyance and an Euler angle of (0°, 90°-150°, 90°±5°). IDTs (Interdigital Electrodes) 3 and 4 and reflectors 5 and 6 are formed on a crystal substrate 2 . The IDTs 3 and 4 and the reflectors 5 and 6 are made of aluminum, the film thickness H / λ normalized to the wavelength of the surface wave is in the range of 0.04 to 0.18, and the plating ratio of the electrode fingers is in the range of 0.53 to 0.87.

[0034] In the surface acoustic wave devic...

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Abstract

Utilizing surface wave device in SH type with its electrode made from aluminum, which is difficult to induce deviation of frequency characteristic caused by deviation of film thick of electrode, the invention provides elastic surface wave device with large electromechanical coupling factor k2 and large reflection coefficient. An electrode constituted from aluminum is formed on crystal base plate with Eulerian angle being as 0 degree, 90-150 degree, 90 minus or plus 5 degree. Normalized film thick H/ lambda is in region 0.04-0.18. The electrode possesses fork finger electrode and reflector, and their metal coating ratio is in region 0.53-0.37.

Description

technical field [0001] The present invention relates to a surface acoustic wave device using SH-type surface waves, and more specifically, to a surface acoustic wave device in which electrodes made of aluminum are formed on a crystal substrate. Background technique [0002] Conventionally, there is known a surface acoustic wave device in which electrodes made of aluminum are formed on an ST-cut X-transported crystal substrate and utilizes surface waves. However, in this surface acoustic wave device, the electromechanical coupling coefficient is small, the reflection coefficient is small, and the insertion loss increases. In addition, when configuring a SAW resonator or a resonator-type surface acoustic wave filter using a reflector, it is necessary to use a reflector with a large number of electrode indices, so miniaturization is difficult. [0003] On the other hand, Patent Document 1 below discloses a surface acoustic wave device using SH-type surface waves by forming ele...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03H9/25
Inventor 门田道雄
Owner MURATA MFG CO LTD
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