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Acoustic surface wave device and communication unit

A surface acoustic wave and surface wave filter technology, applied in the direction of selection devices, electrical components, impedance networks, etc., can solve the problem of increasing the area of ​​the substrate

Inactive Publication Date: 2004-07-28
MURATA MFG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this arrangement of SAW filter devices increases the area of ​​the substrate

Method used

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  • Acoustic surface wave device and communication unit
  • Acoustic surface wave device and communication unit
  • Acoustic surface wave device and communication unit

Examples

Experimental program
Comparison scheme
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Embodiment Construction

[0042] refer to Figure 1 to Figure 8 , the present invention is described in detail by illustrating preferred embodiments.

[0043] first embodiment

[0044] figure 1 is a perspective view showing the structure of a SAW filter as a SAW device according to the first embodiment of the present invention. exist figure 1 In the shown SAW filter, a first SAW filter device 1 and a second SAW filter device 3 (the transmission phase characteristics of which are different from each other by about 180 degrees) are mounted on a piezoelectric substrate 10 .

[0045] The piezoelectric substrate 10 is formed of LiTaO3 cut in the Y direction at 36 degrees to 44 degrees (for example, 39 degrees) and propagated in the X direction, and its thickness is, for example, 285 micrometers. The piezoelectric substrate 10 is not limited to the materials described above, but may be composed of another material exhibiting different piezoelectric characteristics, for example, quartz or LiNbO3.

[00...

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Abstract

In a surface acoustic wave (SAW) apparatus, a first SAW filter device (1) and a second SAW filter device (3) are disposed on a piezoelectric substrate (10) so that the propagation paths are overlapped. When the center-to-center distance between the first and second SAW filter devices (1, 3) are indicated by d1, and when the thickness of the piezoelectric substrate (10) is indicated by t, the first and second SAW filter devices (1, 3) and the piezoelectric substrate (10) are disposed so as to satisfy the condition d1 <= 2.3 x t or d1 >= 2.8 x t.

Description

technical field [0001] The present invention relates to surface acoustic wave (SAW) devices such as SAW filters, and more particularly to those SAW devices having a balanced to unbalanced conversion function with different impedance characteristics at an input and output of the SAW device. The invention also relates to a communication unit using the SAW device described above. Background technique [0002] Significant technological advances have been made in reducing the size and weight of portable communication units such as mobile phones. One way to achieve such progress is to reduce the number and size of the individual components of the communication unit. In addition, components with complex functions are being developed. [0003] Considering this background, to become a SAW filter used at the RF level, it is necessary to use a balanced filter equipped with a function of changing from balanced to unbalanced (called a "balun" function) or equipped with multiple passban...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03H9/25H03H9/00H03H9/02H03H9/145H03H9/64
CPCH03H9/0071H03H9/02866H03H9/0085H03H9/64
Inventor 泽田曜一高崎洋
Owner MURATA MFG CO LTD