JPS6126247B2 - - Google Patents
Info
- Publication number
- JPS6126247B2 JPS6126247B2 JP916584A JP916584A JPS6126247B2 JP S6126247 B2 JPS6126247 B2 JP S6126247B2 JP 916584 A JP916584 A JP 916584A JP 916584 A JP916584 A JP 916584A JP S6126247 B2 JPS6126247 B2 JP S6126247B2
- Authority
- JP
- Japan
- Prior art keywords
- surface wave
- electrode
- unnecessary
- waves
- electrodes
- 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
Links
- 238000010897 surface acoustic wave method Methods 0.000 claims description 5
- 239000000919 ceramic Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000000644 propagated effect Effects 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 239000011358 absorbing material Substances 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- NKZSPGSOXYXWQA-UHFFFAOYSA-N dioxido(oxo)titanium;lead(2+) Chemical compound [Pb+2].[O-][Ti]([O-])=O NKZSPGSOXYXWQA-UHFFFAOYSA-N 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02992—Details of bus bars, contact pads or other electrical connections for finger electrodes
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02614—Treatment of substrates, e.g. curved, spherical, cylindrical substrates ensuring closed round-about circuits for the acoustical waves
- H03H9/02629—Treatment of substrates, e.g. curved, spherical, cylindrical substrates ensuring closed round-about circuits for the acoustical waves of the edges
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02637—Details concerning reflective or coupling arrays
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/125—Driving means, e.g. electrodes, coils
- H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
- H03H9/14517—Means for weighting
- H03H9/14526—Finger withdrawal
Description
【発明の詳細な説明】
本発明は表面波を利用した表面波フイルタの如
き表面波素子に係わる。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface wave element such as a surface wave filter that utilizes surface waves.
この種表面波素子は、例えば第１図に示す如
く、表面波伝播媒質、即ち圧電体基体１上に、
夫々対の櫛歯電極が交互に対向配置されてなる入
力電極２と出力電極３とが被着形成され両電極２
及び３間に接地電極４が配置されて成る。 This type of surface wave element, as shown in FIG.
Input electrodes 2 and output electrodes 3 each having a pair of comb-teeth electrodes arranged opposite to each other are adhered to each other.
A ground electrode 4 is arranged between the electrodes and 3.
この種表面波素子に於いては、その電極２及び
３の各対の櫛歯電極の対向幅Ｗをできるだけ大と
なして入力電極２によつて励起発生した表面波の
うち、直接出力電極３に向う有効表面波のエネル
ギーを大とし、他方向に回折によつて拡がる不要
表面波の反射による不要波の影響をできるだけ小
さくするようにしている。 In this type of surface wave element, the opposing width W of each pair of comb-shaped electrodes of electrodes 2 and 3 is made as large as possible, so that the surface waves excited and generated by the input electrode 2 are directly transmitted to the output electrode 3. The energy of the effective surface waves directed toward is increased, and the influence of unnecessary waves due to reflection of unnecessary surface waves that spread in other directions due to diffraction is minimized.
ところがこのように櫛歯電極の対向幅Ｗを大と
すると、特に、例えばPZT（チタン酸鉛とジルコ
ン酸鉛との固溶体）糸の圧電セラミツクのように
その誘電率εが1000前後という高誘電率を有する
表面波伝播媒質を用いた表面波素子では、そのイ
ンピーダンスが低く外部回路の負担が大きくな
る。 However, when the opposing width W of the comb-teeth electrodes is increased in this way, it is especially important to use piezoelectric ceramics with a dielectric constant ε of around 1000, such as PZT (solid solution of lead titanate and lead zirconate) thread. In a surface wave element using a surface wave propagation medium having , the impedance is low and the load on the external circuit becomes heavy.
そこで、このような圧電セラミツクを用いた表
面波素子ではそのインピーダンスを高めるために
は、櫛歯電極の対向幅Ｗはできるだけ小さくする
ことが望まれる。今、圧電セラミツクを用いて
10.7MHzの表面波フイルタについて述べると、
この場合櫛歯電極の対向幅Ｗが1.5mm以上である
場合は本来の伝搬路を伝わる表面波のエネルギー
が大きいため不要表面波による影響は殆んど問題
にならないが、この幅Ｗを1.0mm以下とすると不
要表面波による影響が大となつてくる。これは回
折により広がつた表面波が音響インピーダンスの
不整合部即ち各電極２，３及び４の縁部、特にほ
ぼ表面波伝播方向（本明細書でいう表面波伝播方
向とは本来の表面波を伝播させるべき方向を指称
し、両電極２及び３を結ぶ方向をいう）に沿つて
延在する両外側縁部２ａ，２ｂ，３ａ，３ｂ及び
４ａ，４ｂにおいての反射が特に大きく影響して
いるのである。 Therefore, in order to increase the impedance of a surface acoustic wave element using such piezoelectric ceramic, it is desired that the opposing width W of the comb-teeth electrodes be made as small as possible. Now, using piezoelectric ceramics
Regarding the 10.7MHz surface wave filter,
In this case, if the opposing width W of the comb-teeth electrodes is 1.5 mm or more, the energy of the surface waves propagating through the original propagation path is large, so the influence of unnecessary surface waves will hardly be a problem, but this width W should be set to 1.0 mm. If the value is below, the influence of unnecessary surface waves will become significant. This is because the surface waves spread by diffraction reach the acoustic impedance mismatched areas, that is, the edges of each electrode 2, 3, and 4, especially in the direction of surface wave propagation (the surface wave propagation direction in this specification refers to the original surface wave direction). Reflection at both outer edges 2a, 2b, 3a, 3b and 4a, 4b extending along the direction in which the electrodes 2 and 3 should be propagated has a particularly large influence. There is.
第２図ないし第８図は夫々表面波速度が2300
m/secの圧電セラミツクによる基体１を用いた
10.7MHzの表面波フイルタの特性（各周波数−
減衰利得）を示すもので、第２図は対向幅Ｗが
2.5mm、距離ｄが550μｍの場合、第３図は、対向
幅Ｗが1.7mm、距離ｄが550μｍの場合、第４図は
対向幅Ｗが1.5mm、距離ｄが550μｍの場合、第５
図は対向幅Ｗが1.0mm、距離ｄが550μｍの場合、
第６図は対向幅Ｗが0.7mm、距離ｄが550μｍの場
合の各特性で、第７図は対向幅Ｗが1.0mm、距離
ｄが600μｍの場合、第８図は対向幅Ｗが0.7mm、
距離ｄが750μｍの場合の各特性で、これら特性
より明らかなように対向幅Ｗが１mm以下では、距
離ｄが550μｍのものでは第５図及び第６図中破
線で囲んで示したように回折、反射の影響ができ
きて、理論通りの特性が得られず、第７図及び第
８図に示す如く対向幅Ｗを１mm以下としてもその
距離ｄを表面波の１波長の３倍及び之に以上に選
定したものにあつては、不要波による影響が取り
除かれていることがわかる。 In Figures 2 to 8, the surface wave velocity is 2300, respectively.
Using the base 1 made of piezoelectric ceramic of m/sec
Characteristics of 10.7MHz surface wave filter (each frequency -
Figure 2 shows the opposing width W
2.5mm and distance d is 550μm, Figure 3 shows the opposite width W is 1.7mm and distance d is 550μm, Figure 4 shows the opposite width W is 1.5mm and distance d is 550μm, and the fifth
The figure shows when the opposing width W is 1.0 mm and the distance d is 550 μm.
Figure 6 shows the characteristics when the facing width W is 0.7 mm and the distance d is 550 μm, Figure 7 shows the characteristics when the facing width W is 1.0 mm and the distance d is 600 μm, and Figure 8 shows the characteristics when the facing width W is 0.7 mm. ,
It is clear from these characteristics that when the distance d is 750 μm, when the facing width W is 1 mm or less, the diffraction occurs as shown by the broken line in Figures 5 and 6 when the distance d is 550 μm. , due to the effect of reflection, it is not possible to obtain the characteristics according to the theory, and as shown in Figs. 7 and 8, even if the opposing width W is 1 mm or less, the distance d is three times one wavelength of the surface wave. It can be seen that the effects of unnecessary waves have been removed in the cases selected above.
尚、ここに各電極２及び３の各櫛歯電極の内側
の縁部２ｃ，２ｄ及び３ｃ，３ｄは、これが櫛歯
によるジグザグパターンを有しているので、この
縁部においては、不要波が散乱されるので、之に
よる影響は殆んどない。 Incidentally, since the inner edges 2c, 2d and 3c, 3d of each comb-teeth electrode of each electrode 2 and 3 have a zigzag pattern due to the comb-teeth, unnecessary waves are not generated at these edges. Since it is scattered, there is almost no effect from this.
上述したように、表面波素子においてその電極
の実効部分即ち櫛歯電極の対向部分から外側縁ま
での距離ｄを、伝播させるべき表面波の波長の３
倍以上とするときは、不要波の影響を回避するこ
とができるが、本発明はこのような構成とするこ
となく或いは、この構成とし更に不要波の影響を
確実に除去することができるようにした表面波素
子を提供せんとするものである。 As mentioned above, in a surface wave element, the distance d from the effective part of the electrode, that is, the opposing part of the comb-shaped electrode, to the outer edge is 3 times the wavelength of the surface wave to be propagated.
If the frequency is doubled or more, the influence of unnecessary waves can be avoided, but the present invention can eliminate the influence of unnecessary waves without using such a configuration or with this configuration. The object of the present invention is to provide a surface wave device with a
即ち、本発明においては、表面波伝播媒質、即
ち圧電基体上に被着された電極のほぼ表面波伝播
方向に沿つて延在する外縁部に表面波の散乱手段
を設ける。 That is, in the present invention, the surface wave scattering means is provided at the outer edge portion of the surface wave propagation medium, that is, the electrode coated on the piezoelectric substrate, extending substantially along the surface wave propagation direction.
第９図を参照して本発明の一例を説明するに、
第１図と対向する部分には同一符号を付して重複
説明を省略する。 An example of the present invention will be described with reference to FIG.
Portions opposite to those in FIG. 1 are denoted by the same reference numerals, and redundant explanation will be omitted.
本発明においては、各電極２，３，４の各外側
縁２ａ，２ｂ，３ａ，３ｂ，４ａ，４ｂを横切る
如く、例えば鋸歯状のジグザグ又は波状のパター
ンを以つて切り溝６をダイヤモンドペン等で各電
極２，３，４の上からこれを切り欠く如く形成し
てここで、不要表面波を散乱させる手段５を形成
する。この場合の周波数特性は第１０図に示す如
く不要波の影響が除去されている。第１１図はこ
の手段５を設けない場合の周波数特性を示したも
のである。 In the present invention, the cut grooves 6 are formed with a diamond pen or the like in a serrated zigzag or wavy pattern, for example, across the outer edges 2a, 2b, 3a, 3b, 4a, 4b of each electrode 2, 3, 4. Then, the electrodes 2, 3, and 4 are cut out from above to form a means 5 for scattering unnecessary surface waves. In this case, the frequency characteristics are such that the influence of unnecessary waves is removed, as shown in FIG. FIG. 11 shows the frequency characteristics when this means 5 is not provided.
尚、本発明は第１２図に示すように、対向幅Ｗ
の短かい櫛歯電極を複数段シリーズに重ねてイン
ピーダンスを高くし、挿入損を減らすようにした
表面波フイルタに本発明を適用することもでき、
この場合にも回折反射の影響を除去することがで
きる。尚、この場合、各電極の内側縁においても
複数の櫛歯が対向し、その伝播方向に沿う直線部
分が比較的長い部分においては手段５を設けるこ
とが望ましい。 Note that, as shown in FIG. 12, the present invention has a facing width W
The present invention can also be applied to a surface wave filter in which short comb-teeth electrodes are stacked in a series of multiple stages to increase impedance and reduce insertion loss.
In this case as well, the influence of diffraction and reflection can be removed. In this case, it is desirable to provide the means 5 at the inner edge of each electrode where a plurality of comb teeth face each other and where the straight line portion along the propagation direction is relatively long.
上述の如く本発明によれば、各電極２，３，４
の少くとも各外側縁２ａ，２ｂ，３ａ，３ｂ，４
ａ，４ｂに不要波の散乱手段５を設けたことによ
つて、不要波の影響を効果的に回避できるので櫛
歯電極の対向幅Ｗを十分小となして、インピーダ
ンスの増大化を図ることができる。したがつて電
極の櫛歯の対向部分から外側縁までの距離ｄを波
長の３倍に選定する要はなく全体の小型化をはか
ることができる。 As described above, according to the present invention, each electrode 2, 3, 4
at least each outer edge 2a, 2b, 3a, 3b, 4
By providing unnecessary wave scattering means 5 in a and 4b, the influence of unnecessary waves can be effectively avoided, so the opposing width W of the comb-teeth electrodes can be made sufficiently small to increase impedance. I can do it. Therefore, it is not necessary to select the distance d from the facing portion of the comb teeth of the electrode to the outer edge to be three times the wavelength, and the overall size can be reduced.
尚、必要に応じて入力及び出力電極の相対向す
る側とは反対側の即ち基体１の表面波伝播方向の
両端部に図示しないが通常の如く、不要波の吸収
材を被着するようになすこともできる。 Incidentally, if necessary, an unnecessary wave absorbing material (not shown) may be coated on the opposite side of the opposing sides of the input and output electrodes, that is, on both ends of the base 1 in the direction of surface wave propagation, as usual. You can also do it.
第１図は従来の表面波素子の略線的上面図、第
２図ないし第８図は夫々その説明に供する周波数
−減衰利得特性曲線図、第９図は本発明による表
面波素子の一例の略線的上面図、第１０図及び第
１１図はその説明に供する周波数−減衰利得特性
曲線図、第１２図は本発明素子の他の例の略線的
上面図である。
１は表面波伝播媒質としての圧電基体、２は入
力電極、２ａ及び２ｂはその外側縁、２ｃ及び２
ｄはその内側縁、３は出力電極、３ａ及び３ｂは
その外側縁、３ｃ及び３ｄはその内側縁、４は接
地電極、４ａ及び４ｂはその外側縁、５は不要波
散乱手段である。
FIG. 1 is a schematic top view of a conventional surface wave device, FIGS. 2 to 8 are frequency-attenuation gain characteristic curve diagrams for explaining the same, and FIG. 9 is an example of a surface wave device according to the present invention. 10 and 11 are frequency-attenuation gain characteristic curve diagrams for explaining the same, and FIG. 12 is a schematic top view of another example of the element of the present invention. 1 is a piezoelectric substrate as a surface wave propagation medium, 2 is an input electrode, 2a and 2b are its outer edges, 2c and 2
d is its inner edge, 3 is an output electrode, 3a and 3b are its outer edges, 3c and 3d are its inner edges, 4 is a ground electrode, 4a and 4b are its outer edges, and 5 is an unnecessary wave scattering means.
Claims (1)
伝播方向に沿う電極端面に上記表面波伝播方向に
延び該伝播方向に非平行な溝による不要波の散乱
手段を設けた表面波素子。1. A surface acoustic wave element, in which an unnecessary wave scattering means is provided on the end face of an electrode that extends in the surface acoustic wave propagation direction and that extends in the surface acoustic wave propagation direction and is non-parallel to the surface acoustic wave propagation direction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP916584A JPS59139714A (en) | 1984-01-20 | 1984-01-20 | Surface wave element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP916584A JPS59139714A (en) | 1984-01-20 | 1984-01-20 | Surface wave element |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14887575A Division JPS5931246B2 (en) | 1975-12-12 | 1975-12-12 | Hyomen Hasoshi |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59139714A JPS59139714A (en) | 1984-08-10 |
| JPS6126247B2 true JPS6126247B2 (en) | 1986-06-19 |
Family
ID=11712998
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP916584A Granted JPS59139714A (en) | 1984-01-20 | 1984-01-20 | Surface wave element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59139714A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0571365B1 (en) * | 1989-11-14 | 1994-10-26 | Siemens Aktiengesellschaft | Surface-wave reflector-filter |
| US9077312B1 (en) * | 2014-07-25 | 2015-07-07 | Resonant Inc. | High rejection surface acoustic wave filter |
-
1984
- 1984-01-20 JP JP916584A patent/JPS59139714A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59139714A (en) | 1984-08-10 |
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