JPH0654858B2 - Surface acoustic wave multiple mode filter - Google Patents
Surface acoustic wave multiple mode filterInfo
- Publication number
- JPH0654858B2 JPH0654858B2 JP11904087A JP11904087A JPH0654858B2 JP H0654858 B2 JPH0654858 B2 JP H0654858B2 JP 11904087 A JP11904087 A JP 11904087A JP 11904087 A JP11904087 A JP 11904087A JP H0654858 B2 JPH0654858 B2 JP H0654858B2
- Authority
- JP
- Japan
- Prior art keywords
- surface acoustic
- acoustic wave
- resonators
- filter
- input
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は弾性表面波共振子を隣接させ，共振子相互間の
音響的結合を利用した弾性表面波多重モードフィルタに
関し，特に，該多重モードフィルタの広帯域化に関す
る。Description: TECHNICAL FIELD The present invention relates to a surface acoustic wave multimode filter that uses surface acoustic wave resonators adjacent to each other and uses acoustic coupling between the resonators, and in particular, the multimode The present invention relates to a wide band of a filter.
従来，弾性表面波共振子間の音響的結合を利用した多重
モードフィルタが提案されている（例えば，H・F・Tierst
en et al 1975 Proc・Ultrasonics Synp・pp 293〜294)。
このタイプのフィルタの比帯域は構成する共振子の幅Ｄ
と共振子間の距離Ｇで決まる。Conventionally, multimode filters that utilize acoustic coupling between surface acoustic wave resonators have been proposed (eg, HF Tierst).
en et al 1975 Proc, Ultrasonics Synp, pp 293-294).
The relative bandwidth of this type of filter is the width D of the constituent resonators.
And the distance G between the resonators.
上述した従来の弾性表面波多重モードフィルタでは，フ
ィルタ帯域を広帯域化するには，共振子の幅Ｄと共振子
間の距離Ｇとを可能な限り狭くする必要がある。しか
し，共振子の幅を狭くすることはフィルタとしての電気
インピーダンスが高くなり，使いにくいという欠点があ
る。また，最も広帯域になるのは共振子の幅Ｄが０λ
（λ：インターディジタル形電極の周期）であり，実質
的に不可能である。In the above-mentioned conventional surface acoustic wave multimode filter, in order to widen the filter band, it is necessary to make the resonator width D and the distance G between the resonators as narrow as possible. However, narrowing the width of the resonator raises the electrical impedance of the filter, which makes it difficult to use. In addition, the widest bandwidth is when the resonator width D is 0λ.
(Λ: period of interdigital electrode), which is practically impossible.
本発明の目的は，各共振子の幅を狭くすることなく，広
帯域化が可能な弾性表面波多重モードフィルタを提供す
ることにある。An object of the present invention is to provide a surface acoustic wave multimode filter capable of widening the band without reducing the width of each resonator.
本発明によれば，圧電基板上に，インターディジタル形
電極を有する弾性表面波共振子を，弾性表面波の伝搬方
向に直角に相隣接するように配置し，前記弾性表面波共
振子相互間の音響的結合を利用した多重モードフィルタ
において，前記弾性表面波共振子の数が３個以上であ
り，かつ，入力用弾性表面波共振子と出力用弾性表面波
共振子が相交互に配置され，前記入力用及び前記出力用
弾性表面波共振子のうち，入力用か出力用かに注目した
機能が同じ共振子同志が互に電気的に並列接続されてい
ることを特徴とする弾性表面波多重モードフィルタが得
られる。According to the present invention, the surface acoustic wave resonators having interdigital electrodes are arranged on the piezoelectric substrate so as to be adjacent to each other at right angles to the propagation direction of the surface acoustic waves, and the surface acoustic wave resonators are arranged between the surface acoustic wave resonators. In a multi-mode filter utilizing acoustic coupling, the number of the surface acoustic wave resonators is three or more, and the input surface acoustic wave resonators and the output surface acoustic wave resonators are alternately arranged in phases. Among the surface acoustic wave resonators for input and output, the resonators having the same function focusing on whether they are for input or output are electrically connected in parallel to each other. A mode filter is obtained.
次に本発明の実施例について図面を参照して説明する。 Next, embodiments of the present invention will be described with reference to the drawings.
第１図を参照すると，本発明の一実施例による弾性表面
波多重モードフィルタは，圧電基板１０上に，形成され
た４個の弾性表面波共振子２１，２２，２３及び２４を
有している。弾性表面波共振子２１，２２，２３及び２
４の各々は，入力用又は出力用インターディジタル形電
極１１又は１２と，その両側に位置する一対の反射器１
３及び１４とを有している。４個のインターディジタル
形電極１１及び１２の各々は，両手の指（電極指）を組
み合わせたような形状の電極である。電極指の各々は，
図示していないが，第１図のＡ−Ａ′ラインに平行に延
びている。本実施例による弾性表面波多重モードフィル
タは，圧電基板１０上に，弾性表面波共振子２１，２
２，２３及び２４を，弾性表面波の伝搬方向（第１図の
Ａ−Ａ′ラインに垂直な方向）に直角に（即ち，横方向
に）相隣接するように配置し，弾性表面波共振子相互間
の音響的結合を利用する。入力用弾性表面波共振子２１
及び２３と出力用弾性表面波共振子２２及び２４とは相
交互に配置されている。入力用弾性表面波共振子２１及
び２３同志は，互に電気的に並列接続されて入力端子Ｉ
Ｎに接続される。出力用弾性表面波共振子２２及び２４
同志も，互に電気的に並列接続されて出力端子ＯＵＴに
接続される。即ち，入力用か出力用かに注目した機能が
同じ共振子同志が互に電気的に接続されている。Referring to FIG. 1, a surface acoustic wave multimode filter according to an exemplary embodiment of the present invention includes four surface acoustic wave resonators 21, 22, 23 and 24 formed on a piezoelectric substrate 10. There is. Surface acoustic wave resonators 21, 22, 23 and 2
Each of 4 is an input or output interdigital electrode 11 or 12 and a pair of reflectors 1 located on both sides thereof.
3 and 14. Each of the four interdigital electrodes 11 and 12 is an electrode shaped like a combination of fingers (electrode fingers) of both hands. Each of the electrode fingers is
Although not shown, it extends parallel to the AA 'line in FIG. The surface acoustic wave multimode filter according to the present embodiment has a surface acoustic wave resonator 21 or 2 on a piezoelectric substrate 10.
2, 23 and 24 are arranged so as to be adjacent to each other at a right angle (that is, in the lateral direction) in the propagation direction of the surface acoustic wave (direction perpendicular to the line AA ′ in FIG. 1), and the surface acoustic wave resonance Utilizes acoustic coupling between the children. Input surface acoustic wave resonator 21
And 23 and the output surface acoustic wave resonators 22 and 24 are alternately arranged in phase. The input surface acoustic wave resonators 21 and 23 are electrically connected in parallel to each other, and the input terminal I
Connected to N. Output surface acoustic wave resonators 22 and 24
Comrades are also electrically connected in parallel to each other and connected to the output terminal OUT. That is, the resonators having the same function focusing on input or output are electrically connected to each other.
第１図の弾性表面波多重モードフィルタは，入力用の弾
性表面波共振子に信号が印加されると，入力用の弾性表
面波共振子には，それぞれ同相の弾性表面波が励振さ
れ，伝搬する。このフィルタは導波路として離散的な固
有モードのみ伝搬可能で，それらのモードの中でも，第
２図にこのフィルタの横モード分布を示したように，上
述の励振分布と結合可能なモード５１，５２のみ伝搬
し，入出力用の弾性表面波共振子間で音響結合され，フ
ィルタとして機能する。なお，５１はS0対称モード，５
２はa1反対称モードを示している。In the surface acoustic wave multimode filter of FIG. 1, when a signal is applied to the input surface acoustic wave resonator, in-phase surface acoustic waves are excited and propagate in the input surface acoustic wave resonators. To do. This filter can propagate only discrete eigenmodes as a waveguide, and among these modes, as shown in the transverse mode distribution of this filter in FIG. It propagates only and is acoustically coupled between the input and output surface acoustic wave resonators and functions as a filter. 51 is the S 0 symmetric mode, 5
2 shows a 1 antisymmetric mode.
本実施例において，例えば，４つの共振子２１，２２，
２３及び２４の横方向の端から端までの距離Ｗが３０入
とすると，導波路としては多数の固有モードが存在し，
例えば第３図のように，対称モードS0，S1，反対称モー
ドa0，a1の計４つある。しかし，第１図に示したよう
に，入力用及び出力用共振子を交互に配置し，電気的に
並列接続することにより，第２図で示すS0モードとa1モ
ードのみ入出力の結合が可能となる。この時，フィルタ
の帯域はS0とa1の周波数上昇率の差η1に相当する。In this embodiment, for example, four resonators 21, 22,
If the distance W from 23 to 24 in the lateral direction is 30, there are many eigenmodes in the waveguide,
For example, as shown in FIG. 3, there are a total of four symmetric modes S 0 and S 1 and antisymmetric modes a 0 and a 1 . However, as shown in FIG. 1, by arranging the input and output resonators alternately and electrically connecting them in parallel, only the S 0 mode and the a 1 mode shown in FIG. Is possible. At this time, the band of the filter corresponds to the difference η 1 between the frequency rise rates of S 0 and a 1 .
他方，第４図に示した従来の弾性表面波多重モードフィ
ルタの場合，モード結合は，第５図に示すように，S0対
称モード６１とa0反対称モード６２であって，第３図に
おいて，Ｓ0とa0の周波数上昇率の差はη2である。On the other hand, in the case of the conventional surface acoustic wave multimode filter shown in FIG. 4, the mode coupling is S 0 symmetric mode 61 and a 0 antisymmetric mode 62 as shown in FIG. In, the difference between the frequency rising rates of S 0 and a 0 is η 2 .
第１図の実施例のη1はη2にくらべ，２〜３倍の値が可
能であり，このことは本発明により，この種のフィルタ
の大幅な広帯域化が可能となり，設計に自由度を与える
ことができることを示している。The value of η 1 in the embodiment shown in FIG. 1 can be two to three times as large as that of η 2 , which means that the present invention allows a wide band of this type of filter to be provided, and the degree of freedom in design. Shows that can be given.
なお，従来，第４図の２重モードフィルタを電気的に直
列接続した第６図に示す２重モード２段フィルタがある
が，広帯域化は不可能であり，本発明とのちがいは明ら
かである。Conventionally, there is a dual-mode two-stage filter shown in FIG. 6 in which the dual-mode filter of FIG. 4 is electrically connected in series, but it is impossible to broaden the band and the difference from the present invention is clear. is there.
第７図を参照すると，本発明の他の実施例による弾性表
面波多重モードフィルタは，３個の弾性表面波共振子３
１，３２及び３３で構成され，出力用インターディジタ
ル形電極１２同志が互に電気的に並列接続されている。
この第７図のフィルタも，第１図のフィルタと同様に機
能し，フィルタ帯域の広帯域化が可能となる。Referring to FIG. 7, a surface acoustic wave multimode filter according to another embodiment of the present invention includes three surface acoustic wave resonators 3.
1, 32, and 33, and the output interdigital electrodes 12 are electrically connected in parallel to each other.
The filter shown in FIG. 7 also functions similarly to the filter shown in FIG. 1, and the filter band can be broadened.
以上説明したように，本発明では，各共振子の幅を狭く
することなく，フィルタ帯域の広帯域化が可能な弾性表
面波多重モードフィルタが得られる。As described above, according to the present invention, it is possible to obtain the surface acoustic wave multimode filter capable of widening the filter band without narrowing the width of each resonator.
第１図は本発明の一実施例による弾性表面波多重モード
フィルタの構成図，第２図は第１図のフィルタのＡ−
Ａ′面で見たモード分布を示した図，第３図は第１図の
フィルタの機能を説明するために，モード毎の周波数上
昇率の導波路幅Ｗとの関係を示した図，第４図は従来の
弾性表面波多重モードフィルタの構成図，第５図は第４
図の弾性表面波多重モードフィルタのＢ−Ｂ′面で見た
モード分布を示した図，第６図は従来の別の弾性表面波
多重モードフィルタの構成図，第７図は本発明の他の実
施例による弾性表面波多重モードフィルタの構成図であ
る。 １０……圧電基板，１１……入力用インターディジタル
形電極，１２……出力用インターディジタル形電極，１
３及び１４……反射器，２１，２２，２３，２４，３
１，３２及び３３……弾性表面波共振子。FIG. 1 is a block diagram of a surface acoustic wave multimode filter according to an embodiment of the present invention, and FIG. 2 is an A- of the filter of FIG.
FIG. 3 is a diagram showing the mode distribution as seen on the A ′ plane, and FIG. 3 is a diagram showing the relationship between the frequency rise rate for each mode and the waveguide width W in order to explain the function of the filter of FIG. FIG. 4 is a block diagram of a conventional surface acoustic wave multimode filter, and FIG.
FIG. 6 is a diagram showing the mode distribution of the surface acoustic wave multimode filter seen on the BB ′ plane, FIG. 6 is a block diagram of another conventional surface acoustic wave multimode filter, and FIG. 7 is another example of the present invention. FIG. 3 is a configuration diagram of a surface acoustic wave multimode filter according to the example of FIG. 10 ... Piezoelectric substrate, 11 ... Input interdigital electrode, 12 ... Output interdigital electrode, 1
3 and 14 ... Reflectors, 21, 22, 23, 24, 3
1, 32 and 33 ... Surface acoustic wave resonator.
Claims (1)
を有する弾性表面波共振子を，弾性表面波の伝搬方向に
直角に相隣接するように配置し，前記弾性表面波共振子
相互間の音響的結合を利用した弾性表面波多重モードフ
ィルタにおいて，前記弾性表面波共振子の数が３個以上
であり，かつ，入力用弾性表面波共振子と出力用弾性表
面波共振子が相交互に配置され，前記入力用及び前記出
力用弾性表面波共振子のうち，入力用か出力用かに注目
した機能が同じ共振子同志が互に電気的に並列接続され
ていることを特徴とする弾性表面波多重モードフィル
タ。1. A surface acoustic wave resonator having an interdigital electrode is disposed on a piezoelectric substrate so as to be adjacent to each other at right angles to the propagation direction of the surface acoustic wave, and the acoustic waves between the surface acoustic wave resonators are mutually adjacent. In a surface acoustic wave multi-mode filter using dynamic coupling, the number of the surface acoustic wave resonators is three or more, and the surface acoustic wave resonators for input and the surface acoustic wave resonators for output are arranged alternately. Among the surface acoustic wave resonators for input and output, the resonators having the same function focusing on input or output are electrically connected in parallel to each other. Wave multimode filter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11904087A JPH0654858B2 (en) | 1987-05-18 | 1987-05-18 | Surface acoustic wave multiple mode filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11904087A JPH0654858B2 (en) | 1987-05-18 | 1987-05-18 | Surface acoustic wave multiple mode filter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63285018A JPS63285018A (en) | 1988-11-22 |
| JPH0654858B2 true JPH0654858B2 (en) | 1994-07-20 |
Family
ID=14751457
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11904087A Expired - Lifetime JPH0654858B2 (en) | 1987-05-18 | 1987-05-18 | Surface acoustic wave multiple mode filter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0654858B2 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02182012A (en) * | 1989-01-06 | 1990-07-16 | Murata Mfg Co Ltd | Surface acoustic wave device |
| JPH0767060B2 (en) * | 1989-10-03 | 1995-07-19 | 国際電気株式会社 | Single-mode two-terminal pair surface acoustic wave resonator and surface acoustic wave filter |
| US5374908A (en) * | 1992-11-25 | 1994-12-20 | Rf Monolithics, Inc. | Surface acoustic wave device for generating an output signal with only a symmetric or only an asymmetric vibration mode acoustic wave |
| DE69424737T2 (en) * | 1993-10-08 | 2000-09-28 | Matsushita Electric Ind Co Ltd | Acoustic surface wave filter |
| FR2739232B1 (en) * | 1995-09-26 | 1997-10-24 | Thomson Csf | SURFACE ACOUSTIC WAVE FILTER USING THE COUPLING OF THREE ACOUSTIC CHANNELS |
| US6348845B2 (en) * | 1996-05-23 | 2002-02-19 | Matsushita Electric Industrial Co., Ltd. | Surface acoustic wave filter and multistage surface acoustic wave filter |
| US6801100B2 (en) | 1996-05-23 | 2004-10-05 | Matsushita Electric Industrial Co., Ltd. | Inter-digital transducer, surface acoustic wave filter and communication apparatus using the same |
| JP3154402B2 (en) * | 1997-11-12 | 2001-04-09 | 日本電気株式会社 | SAW filter |
-
1987
- 1987-05-18 JP JP11904087A patent/JPH0654858B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63285018A (en) | 1988-11-22 |
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