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Surfac acoustic wave device and communication device comprising same

A surface acoustic wave, resonator technology, applied in impedance networks, piezoelectric devices/electrostrictive devices, electrical components, etc., can solve problems such as balance deterioration

Inactive Publication Date: 2006-02-08
MURATA MFG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0012] However, in the above structure, since the phase of the resonator filter 110 is 180° different from that of the resonator filter 100, the signal terminal and the ground of the electrode fingers in the IDT 111 at the center of the resonator filter 110 are For the resonator type filter 100 reversed, therefore, it includes the situation that the number of signal terminals and grounding of the resonator type filter 100 and the resonator type filter 110 are different and the signal terminal and grounding in the boundary between IDT and IDT Factors that deteriorate the balance, such as the case where an unnecessary electric field is generated by paralleling
As a countermeasure to improve the balance, there is still a method of grounding the electrode finger of the signal terminal, but there is a problem in the balance

Method used

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  • Surfac acoustic wave device and communication device comprising same
  • Surfac acoustic wave device and communication device comprising same
  • Surfac acoustic wave device and communication device comprising same

Examples

Experimental program
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no. 1 approach

[0062] Based on Figure 1 to Figure 7 The description of the first embodiment of the present invention is as follows. The surface acoustic wave device (SAW device) having an unbalanced-balanced conversion function according to this embodiment is shown in FIG. 1, and its structure includes resonator-type filters (surface acoustic wave elements, SAW filters) 1, 2 . These resonator-type filters 1 and 2 have substantially equal passbands. In addition, these resonator-type filters 1 and 2 are provided on a piezoelectric substrate (not shown). The piezoelectric substrate is composed of lithium tantalate, lithium niobate, and the like.

[0063] The above-mentioned resonator filter 1 has IDT 11 as the center, and IDTs 12 and 13 are arranged on the left and right (left and right along the surface acoustic wave propagation direction) of the IDT 11. These IDTs 11, 12, and 13 are provided with reflectors 14, 14 from left and right (left and right along the surface acoustic wave propagation di...

no. 2 approach

[0083] Based on Figure 8 to Picture 10 Descriptions of other embodiments of the present invention are as follows. In addition, for convenience of description, the same reference numerals are given to the components having the same functions as the components shown in the above-mentioned first embodiment, and the description thereof will be omitted.

[0084] In this embodiment, the surface acoustic wave device of the first embodiment has substantially the same design, and includes a resonator 31a connected to the side of the unbalanced signal terminal 7 and traps 32 and 32 sandwiching it. The resonator 3 is changed to a trap resonator 3a including a resonator 31a and reflectors 32a and 32a sandwiching it. The above-mentioned resonator 31 and the resonator 31a have different crossing widths. In this way, in order to study the balance of the crossing widths in the notch resonators 3a and 4, a specific example will be used for description. Table 3 shows the design parameters in the a...

no. 3 approach

[0090] based on Figure 14 to Figure 21 Descriptions of other embodiments of the present invention are as follows.

[0091] The surface acoustic wave device (SAW device) having an unbalanced-balanced conversion function according to this embodiment is as Picture 14 As shown, the LiTaO propagated in YcutX by 40±5° 3 The piezoelectric substrate (not shown) is composed of longitudinally coupled resonator-type surface acoustic wave filters (surface acoustic wave elements) 501 and 502 formed by Al electrodes. The impedance of the unbalanced signal end is 50Ω, and the impedance of the balanced signal end is 50Ω. It is a 150Ω balanced-unbalanced signal conversion function. In addition, surface acoustic wave resonators (resonators) 503 and 504 are connected in series between the unbalanced signal terminal 515 and the longitudinally coupled resonator-type surface acoustic wave filters 501 and 502, respectively.

[0092] The above-mentioned longitudinally coupled resonator-type surface aco...

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Abstract

A surface acoustic wave device has an unbalanced-to-balanced conversion function, which is capable of improving balanced characteristics, includes a first resonator filter and a second resonator filter, having a plurality of interdigital transducers disposed along the propagation direction of a surface acoustic wave. The surface acoustic wave device has an unbalanced-to-balanced conversion function as a result of the phase of the second resonator filter being reversed by 180 DEG with respect to that of the first resonator filter. The surface acoustic wave device further includes a first resonator connected in series to an unbalanced signal terminal side of the first resonator filter, and a second resonator connected in series to an unbalanced signal terminal side of the second resonator filter. The first resonator and the second resonator have different design parameters.

Description

Technical field [0001] The present invention relates to a surface acoustic wave device used in delay lines, filters, etc., and a communication device having the surface acoustic wave device. Background technique [0002] In recent years, due to the miniaturization and weight reduction of electronic devices, electronic components are also required to be multifunctional. In this context, surface acoustic wave filters (hereinafter referred to as SAW filters) as surface acoustic wave devices used in communication devices such as mobile phones are also required to have an unbalanced-balanced conversion function. In order to achieve direct connection with ICs that work according to balanced inputs, research on them has become active. [0003] In particular, in a SAW device with an unbalanced-balanced conversion function composed of a resonator filter, the amplitude difference and phase difference on the balanced side become important characteristics (hereinafter referred to as balance)...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03H9/25H03H9/64H03H9/145H10N30/00
CPCH03H9/0071H03H9/14582H03H9/25
Inventor 柴田治高峰裕一
Owner MURATA MFG CO LTD
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