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Surface acoustic wave device

A surface acoustic wave device and filter technology, which is applied to electrical components, impedance networks, etc., can solve problems such as insertion loss degradation

Active Publication Date: 2013-10-02
TAIYO YUDEN KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In this case, a notch may be generated in the passband, and insertion loss may deteriorate

Method used

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  • Surface acoustic wave device
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Examples

Experimental program
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Effect test

no. 1 example

[0032] figure 2 is a top view illustrating the configuration of the SAW device 100A according to the first embodiment. The basic configuration of the SAW device 100A is the same as that of the SAW device 100a according to the first comparative example. Accordingly, the same components are assigned the same reference numerals, and descriptions thereof are omitted.

[0033] The configuration of the first input IDT 22A in the first filter 20A of the SAW device 100A according to the first embodiment is different from that of the first input IDT 22a in the first filter 20a of the first comparative example. More specifically, the number of electrode fingers of the input electrode 23A is larger than that of the ground electrode 24A, and the total number of electrode fingers in the IDT is an odd number. In the second input IDT 42A, the number of electrode fingers of the input electrode 43A is the same as that of the ground electrode 44A, and like the first comparative example, the ...

no. 2 example

[0042] The second embodiment is an example of a SAW device in which a resonator is combined to a filter.

[0043] Figure 4 is a top view of the SAW device 100B according to the second embodiment. The same components as those of the first embodiment are assigned the same reference numerals and their detailed descriptions are omitted. The first resonator 70 is connected between the unbalanced terminal 10 and the first filter 20B and between the unbalanced terminal 10 and the second filter 40B. The first resonator 70 includes a pair of IDTs 72 and reflectors 74 located on both sides of the IDTs 72 . Also, the second resonator 80 including the IDT 82 and the reflector 84 is connected between the first balanced terminal 12 and the first filter 20B. A third resonator 90 including an IDT 92 and a reflector 94 is connected between the second balanced terminal 14 and the second filter 40B. Out-of-band noise can be reduced (increased attenuation) by combining resonators into filter...

no. 3 example

[0058] Like the second embodiment, the third embodiment is an example of a SAW device in which a resonator is combined to a filter.

[0059] Figure 11 is a top view of a SAW device 100C according to the third embodiment. The basic configuration of the SAW device 100C is the same as that of the SAW device 100B according to the second embodiment. Therefore, the same components as those of the second embodiment are assigned the same reference numerals, and their detailed descriptions are omitted.

[0060] The configuration of the first input IDT 22C in the first filter 20C of the SAW device 100C is different from that of the first input IDT 22B of the first filter 20B of the second embodiment. More specifically, like the second embodiment, the total number of electrode fingers in the first input IDT 22C is an odd number, but the number of electrode fingers of the ground electrode 24 is greater than that of the input electrode 23C. Other configurations (configurations of the f...

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Abstract

A surface acoustic wave device (100A) includes a first filter (20A) and a second filter (40A), each of them being a surface acoustic wave (SAW) filter including an odd number of at least three InterDigital Transducers (IDTs); an unbalanced terminal (10) to which an unbalanced signal is input; a first balanced terminal (12) from which a signal having a same phase as the unbalanced signal is output; and a second balanced terminal (14) from which a signal having an opposite phase to the unbalanced signal is output. One of electrodes of a first center IDT and one of electrodes of a second center IDT are commonly connected to the unbalanced terminal, the first center IDT and the second center IDT being one out of the odd number of IDTs and locating at a center in the first filter and the second filter respectively. The number of electrode fingers of the first center IDT is an odd number, and the number of electrode fingers of the second center IDT is an even number.

Description

technical field [0001] The present invention relates to surface acoustic wave devices. Background technique [0002] In recent years, as wireless communication devices such as mobile phones have been continuously upgraded, surface acoustic wave (SAW) devices as components are required to have a function of converting an unbalanced signal into a balanced signal, that is, a balanced-unbalanced converter (balun) function . The balun function is realized by connecting two SAW filters in parallel between one unbalanced terminal and two balanced terminals. The in-band insertion loss is reduced by making the number of electrode fingers of an interdigital transducer (IDT) constituting a SAW filter differ from one filter to another. WO2006 / 087875 (Document 1) discloses such a SAW device. [0003] In the SAW device disclosed in Document 1, the numbers of electrode fingers of the IDTs constituting the two SAW filters are both even or odd. In this case, a notch may be generated in t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03H9/25
CPCH03H9/0071H03H9/6436H03H9/0085
Inventor 高桥直树
Owner TAIYO YUDEN KK