Surface acoustic wave apparatus

A surface acoustic wave device and surface acoustic wave technology, applied in electrical components, impedance networks, etc., can solve the problem of increasing the number of circuit components in wireless devices

Inactive Publication Date: 2008-09-03
TAIYO YUDEN KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In this case, increasing the number of circuit elements of the wireless device

Method used

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  • Surface acoustic wave apparatus
  • Surface acoustic wave apparatus
  • Surface acoustic wave apparatus

Examples

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Embodiment Construction

[0039] Preferred embodiments of the present invention are described hereinafter with reference to the accompanying drawings.

[0040] Figure 4 shows an embodiment of the invention in which the first feature of the invention is implemented. Although similar to FIG. 1 in which only the electrode structure is shown, a surface acoustic wave device was formed on a piezoelectric substrate having the electrode structure in a manner similar to FIG. 2 . This also applies to the following embodiments, in which only the electrode structure is shown for the purpose of simplifying the illustration.

[0041] In FIG. 4 , the embodiment consists of an input IDT 300 , an input IDT 301 and a balanced output IDT 200 . The IDT 200 includes a first split-lobe IDT 201 and a second split-lobe IDT 202 connected in series.

[0042] In addition, the impedance in FIG. 4 will be described below. The impedances of the input IDTs 300, 301 provided on both sides are 100Ω, respectively. Connecting the inp...

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Abstract

Improvement on an insertion loss, as well as phase balance, is obtained in surface acoustic wave device. In the surface acoustic wave device, when an aperture length of the electrode fingers of an interdigital transducer for input or an interdigital transducer for output is defined as X, the interdigital transducer for input or the interdigital transducer for output includes two split interdigital transducers respectively including electrode fingers having an aperture length of approximately X / 2, and electrodes of respective electrode fingers in the first and second split interdigital transducers are extracted from the two split interdigital transducers, and disposed in such a way as signals in the two outputs or inputs connected to a balanced terminal pair have a phase difference of 180 DEG , and the two split interdigital transducers are connected in series by a common electrode of solid shape, of which electrode width is greater than twice the pitch of the electrode fingers in the two split interdigital transducers, and further the common electrode is connected to the ground potential.

Description

technical field [0001] The present invention relates to surface acoustic wave devices, and more particularly to surface acoustic wave devices with differential terminal pairs. Background technique [0002] Currently, surface acoustic wave devices are widely used as devices having a filtering function in high-frequency circuits of wireless devices (represented by cellular phones as an application example). In recent years, integrated circuit (IC) elements with balanced or differential input / output have been used in high-frequency circuits of such wireless equipment. [0003] In contrast, a conventional filter using a surface acoustic wave device (hereinafter referred to as a SAW filter as the case may be) employs unbalanced terminals for both input and output terminals. Thus, a component called a balun for unbalanced-to-balanced conversion, or a balun-to-balanced converter made of discrete components, needs to be used. [0004] In addition, a SAW filter generally has an inp...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03H9/64H03H9/145H03H9/00
CPCH03H9/14591H03H9/02992H03H9/0028H03H9/0061H03H9/0042H03H9/145H03H9/64
Inventor 川内治田岛基行阿部卓也
Owner TAIYO YUDEN KK
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