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Acoustic surface wave filter device

A surface acoustic wave filtering and surface wave filter technology, which is applied to electrical components, impedance networks, etc., can solve problems such as the difficulty of reducing the size, the increase in the size of the surface acoustic wave filter device 500, and the increase in the cost of the surface acoustic wave filter device. , to achieve the effect of improving the phase balance

Inactive Publication Date: 2002-10-30
MURATA MFG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, the size of the surface acoustic wave filter device 500 is significantly increased, making size reduction difficult.
In addition, due to the reduction in the number of surface acoustic wave filter devices made from one wafer, the cost of manufacturing is significantly increased.

Method used

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Examples

Experimental program
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Embodiment Construction

[0058] Referring to the accompanying drawings, the present invention will be discussed in terms of certain preferred embodiments of the surface acoustic wave filter device of the present invention.

[0059] figure 1 is a schematic plan view of the surface acoustic wave filter device according to the first preferred embodiment of the present invention.

[0060] By preparing on the piezoelectric substrate 100a such as figure 1 With the electrode structure shown, a first surface acoustic wave filter element 101 and a second surface acoustic wave filter element 102 are provided in the surface acoustic wave filter device 100 . In this preferred embodiment, the first surface acoustic wave filter element 101 has first IDT111 to third IDT113 arranged along the surface acoustic wave propagation direction, and the second surface acoustic wave filter element 102 has The transmission direction is set from the first IDT114 to the third IDT116. In addition, in the first surface acousti...

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PUM

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Abstract

A surface acoustic wave filter device has a balanced to unbalanced conversion function, and the device has different input / output impedances and good balance in the pass band. The surface acoustic wave filter device has a balanced-to-unbalanced conversion function, and in this device, the interval of the input / output IDT of the second surface acoustic wave filter element is larger than that of the input / output IDT of the first surface acoustic wave filter element. spaced about half the wavelength of the surface acoustic wave so that the phase is reversed, wherein the total electrostatic capacitance value of the plurality of IDTs of the second surface acoustic wave filter element is greater than the total of the plurality of IDTs of the first surface acoustic wave filter element electrostatic capacitance value.

Description

technical field [0001] The present invention relates to surface acoustic wave filter devices, eg bandpass filters for mobile phones. More specifically, the present invention relates to a surface acoustic wave filter device having a characteristic impedance of an input side different from that of an output side and having an unbalanced-to-balanced conversion function. Background technique [0002] In recent years, in order to reduce the size of the mobile phone, the number of components and the size of the components used in the mobile phone combination unit have been reduced and a combination unit having multiple functions has been developed. [0003] Among the surface acoustic wave filter devices applied in RF stages of mobile phones, surface acoustic wave filter devices having an unbalanced-to-balanced conversion function have been used. [0004] In mobile phones, the portion from the antenna to the surface acoustic wave filter used as a bandpass filter is defined as an u...

Claims

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Application Information

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IPC IPC(8): H03H9/00H03H9/145H03H9/25H03H9/64
CPCH03H9/0071H03H9/0085H03H9/14582H03H9/6436H03H9/64
Inventor 泽田曜一高峰裕一
Owner MURATA MFG CO LTD
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