JPH069329B2 - Surface acoustic wave device - Google Patents
Surface acoustic wave deviceInfo
- Publication number
- JPH069329B2 JPH069329B2 JP23894684A JP23894684A JPH069329B2 JP H069329 B2 JPH069329 B2 JP H069329B2 JP 23894684 A JP23894684 A JP 23894684A JP 23894684 A JP23894684 A JP 23894684A JP H069329 B2 JPH069329 B2 JP H069329B2
- Authority
- JP
- Japan
- Prior art keywords
- electrode
- surface acoustic
- acoustic wave
- electrode fingers
- wave device
- 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、通信機器等に用いられる表面弾性波デバイス
に関するものである。Description: TECHNICAL FIELD The present invention relates to a surface acoustic wave device used for communication equipment and the like.
従来例の構成とその問題点 近年、通信機器等の部品点数削減、高品質化のために、
表面弾性波デバイスが多く用いられるようになってきて
いるが、さらに高性能化、低コスト化への要望が高まっ
てきている。Configuration of conventional example and its problems In recent years, in order to reduce the number of parts such as communication equipment and to improve quality,
Although surface acoustic wave devices have been widely used, there is an increasing demand for higher performance and lower cost.
このような従来の表面弾性波デバイスについて、第４図
を用いて説明する。第４図は従来の表面弾性波デバイス
におけるフィルタ素子の平面図で、１は圧電基板、２は
重み付け電極、３はダミー電極である。Such a conventional surface acoustic wave device will be described with reference to FIG. FIG. 4 is a plan view of a filter element in a conventional surface acoustic wave device, in which 1 is a piezoelectric substrate, 2 is a weighting electrode, and 3 is a dummy electrode.
しかしながらこのような従来構成では、重み付け電極２
全体にわたって等ピッチの電極指が存在するため、特に
重み付け電極２の対数が多いときには、電極指による反
射のため、通過帯域内にリップルを生じる。すなわち、
スプリット型電極の場合、反射波の位相は90゜ずれてい
るため、キャンセルされてリップルは生じないはずであ
るが、現実には対数が多くなると電極指の反射によるリ
ップルも大きくなる。一方、ダミー電極３を設けない構
造では、中心軸近くを伝播する波とエッジ部分を伝播す
る波とでは、伝播速度がちがうため、波面の歪みを生
じ、周波数特性が劣化する。またスプリット型電極にす
ると、電極指の幅がλ／８になるため、断線しやすくな
り、歩留りが低下する。However, in such a conventional configuration, the weighting electrode 2
Since there are electrode fingers having an equal pitch over the whole, particularly when the number of pairs of weighting electrodes 2 is large, ripples occur in the pass band due to reflection by the electrode fingers. That is,
In the case of a split type electrode, since the phase of the reflected wave is shifted by 90 °, it should be canceled and no ripple should occur, but in reality, when the logarithm increases, the ripple due to the reflection of the electrode finger also increases. On the other hand, in the structure in which the dummy electrode 3 is not provided, the propagation speed is different between the wave propagating near the central axis and the wave propagating at the edge portion, which causes distortion of the wavefront and deteriorates the frequency characteristic. Further, when the split type electrode is used, the width of the electrode finger becomes λ / 8, so that the wire easily breaks and the yield decreases.
発明の目的 本発明は上記従来の欠点を解消するもので、電極指の反
射によって生じるリップルを低減し、かつ波面の歪みに
よる周波数特性の劣化をなくし、さらに歩留りを向上さ
せることのできる表面弾性波デバイスを提供することを
目的とする。An object of the present invention is to solve the above-mentioned conventional drawbacks, and to reduce the ripple caused by the reflection of the electrode finger, eliminate the deterioration of the frequency characteristics due to the distortion of the wavefront, and further improve the yield. Intended to provide the device.
発明の構成 上記目的を達成するため、本発明の表面弾性波デバイス
は、圧電基板上に少なくともスプリット型のアポダイズ
型重み付け電極を備え、この重み付け電極の交叉してい
ない分の電極指の幅をλ／２とし、かつ前記電極指の交
叉していない部分の電極指間隔を３λ／８と５λ／８と
の交互の繰り返しとしたものである。To achieve the above object, the surface acoustic wave device of the present invention is provided with at least a split-type apodized weighting electrode on a piezoelectric substrate, and the width of the electrode fingers for which the weighting electrodes do not intersect is λ. / 2, and the electrode finger interval in the portion where the electrode fingers do not intersect is alternately repeated 3λ / 8 and 5λ / 8.
実施例の説明 以下、本発明の一実施例について、図面に基づいて説明
する。Description of Embodiments An embodiment of the present invention will be described below with reference to the drawings.
第１図は本発明の一実施例における表面弾性波デバイス
のフィルタ素子の平面図、第２図は同要部拡大平面図
で、11は圧電基板、12は重み付け電極、13は幅がλ／２
の電極指である。FIG. 1 is a plan view of a filter element of a surface acoustic wave device according to an embodiment of the present invention, and FIG. 2 is an enlarged plan view of the essential part of the same, where 11 is a piezoelectric substrate, 12 is a weighting electrode, and 13 is a width λ / Two
Electrode fingers.
まず、ダミー電極を設けないと、電極内の反射は少なく
なるが、波面の歪みが生じるので、それを補償するため
に、交叉していない部分での電極指13の幅をλ／２にし
ている。このようにすると、電極指が交叉している部分
も交叉していない部分も、金属薄膜におおわれている部
分とおおわれていない部分との比が１：１になるので、
波の伝播速度は一様になり、波面の歪みは生じない。し
かしながら、λ／２の幅の電極指13が等間隔で並んでい
ると、その反射波は同位相となるので、リップルが生じ
やすい。そこで、交叉していない部分での電極指１３と
電極指１３との間隔が３λ／８と５λ／８との交互の繰
り返しになるように配置している。このようにすれば、
反射波の位相が90゜ずれるので、互いにキャンセルされ
てリップルが小さくなる。スプリット型のダミー電極で
も位相は90゜ずれるが、λ／２の線幅の電極に対して本
数が４倍になるので、リップルが生じやすい。またスプ
リット型電極にくらべて４倍の線幅になるので、それだ
け断線しにくくなり、歩留りが向上すると同時に、電気
抵抗も小さくなるので挿入損失も小さくなる。First, if the dummy electrode is not provided, the reflection in the electrode is reduced, but the wavefront distortion occurs. Therefore, in order to compensate for it, the width of the electrode finger 13 at the non-intersecting portion is set to λ / 2. There is. By doing so, the ratio of the portion where the electrode fingers are crossed and the portion where the electrode fingers are not crossed is 1: 1 because of the ratio of the portion covered with the metal thin film and the portion not covered with the metal thin film.
The wave propagation velocity becomes uniform and no wavefront distortion occurs. However, when the electrode fingers 13 having a width of λ / 2 are arranged at equal intervals, the reflected waves have the same phase, so that ripples are likely to occur. Therefore, the electrode fingers 13 are arranged so that the intervals between the electrode fingers 13 at the non-intersecting portions are alternately repeated 3λ / 8 and 5λ / 8. If you do this,
Since the phases of the reflected waves are shifted by 90 °, they cancel each other and the ripple becomes smaller. Even with a split type dummy electrode, the phase shifts by 90 °, but since the number of electrodes is four times that of an electrode having a line width of λ / 2, ripples are likely to occur. Further, since the line width is four times as large as that of the split type electrode, it is more difficult to break the wire, and the yield is improved, and at the same time, the electric resistance is decreased and the insertion loss is also decreased.
また電極指を間引く場合、第３図に破線で示すように、
電極指が交叉していない部分で相隣接する２本の電極指
を含む電極指対を一組として間引く。このようにする
と、中心軸付近を通過する波とエッジ部分を通過する波
とで波面の歪みが生ずることもなく、また電極指が交叉
していない部分ではそれぞれの電極指で反射される波の
位相は互いに90゜ずれているので、リップルは少なくな
る。When thinning out the electrode fingers, as shown by the broken line in FIG.
An electrode finger pair including two electrode fingers that are adjacent to each other in a portion where the electrode fingers do not cross each other is thinned out as a set. In this way, wavefront distortion does not occur between the wave passing through the central axis and the wave passing through the edge portion, and the wave reflected by each electrode finger does not intersect in the portion where the electrode fingers do not intersect. Since the phases are 90 ° out of phase with each other, there is less ripple.
発明の効果 以上説明したように本発明によれば、スプリット型の重
み付け電極の交叉していない部分の電極指の幅をλ／２
にし、その電極指の間隔を３λ／８と５λ／８との交互
の繰り返しにしたので、波面の歪みを生ずることなく、
リップルを低減することができ、交叉していない部分で
は電極指の幅が太くなるための断線しにくくなって歩留
りが向上し、また電気抵抗も小さくなるため挿入損失も
小さくなる。EFFECTS OF THE INVENTION As described above, according to the present invention, the width of the electrode finger of the portion where the split type weighting electrodes do not intersect is λ / 2.
Since the distance between the electrode fingers is alternately repeated 3λ / 8 and 5λ / 8, the wavefront is not distorted.
Ripple can be reduced, and the width of the electrode fingers in the non-intersecting portion becomes thicker so that disconnection is less likely to occur, the yield is improved, and the electrical resistance is also reduced, so that the insertion loss is also reduced.
第１図は本発明の一実施例における表面弾性波デバイス
のフィルタ素子の平面図、第２図は同要部拡大平面図、
第３図は同フィルタ素子の電極指を間引いた状態の要部
の平面図、第４図は従来の表面弾性波デバイスにおける
フィルタ素子の平面図である。 11…圧電基板、12…重み付け電極、13……幅がλ／２の
電極指FIG. 1 is a plan view of a filter element of a surface acoustic wave device according to an embodiment of the present invention, and FIG.
FIG. 3 is a plan view of a main part of the filter element with electrode fingers thinned out, and FIG. 4 is a plan view of a filter element in a conventional surface acoustic wave device. 11 ... Piezoelectric substrate, 12 ... Weighting electrode, 13 ... Electrode finger with width λ / 2
Claims (2)
ポダイズ型重み付け電極を備え、この重み付け電極の交
叉していない部分の電極指の幅をλ／２（λは表面弾性
波の波長）とし、かつ前記電極指の交叉していない部分
の電極指間隔を３λ／８と５λ／８との交互の繰り返し
とした表面弾性波デバイス。1. A piezoelectric substrate is provided with at least a split type apodized weighting electrode, and a width of an electrode finger of a portion where the weighting electrodes do not intersect is λ / 2 (λ is a wavelength of a surface acoustic wave), and A surface acoustic wave device in which an electrode finger interval of a portion where the electrode fingers do not intersect is alternately repeated at 3λ / 8 and 5λ / 8.
も相隣り合う２本の電極指を含む電極指対を一組として
間引いた特許請求の範囲第１項記載の表面弾性波デバイ
ス。2. The surface acoustic wave device according to claim 1, wherein a pair of electrode fingers including at least two electrode fingers adjacent to each other is thinned out as a set at a portion where the electrode fingers do not cross each other.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23894684A JPH069329B2 (en) | 1984-11-13 | 1984-11-13 | Surface acoustic wave device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23894684A JPH069329B2 (en) | 1984-11-13 | 1984-11-13 | Surface acoustic wave device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61117912A JPS61117912A (en) | 1986-06-05 |
| JPH069329B2 true JPH069329B2 (en) | 1994-02-02 |
Family
ID=17037631
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23894684A Expired - Lifetime JPH069329B2 (en) | 1984-11-13 | 1984-11-13 | Surface acoustic wave device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH069329B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5051644A (en) * | 1990-04-19 | 1991-09-24 | R. F. Monolithics, Inc. | Electrode structure with constant velocity and predetermined reflectivity |
-
1984
- 1984-11-13 JP JP23894684A patent/JPH069329B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61117912A (en) | 1986-06-05 |
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