JPH06303083A - Surface acoustic wave element - Google Patents
Surface acoustic wave elementInfo
- Publication number
- JPH06303083A JPH06303083A JP8769193A JP8769193A JPH06303083A JP H06303083 A JPH06303083 A JP H06303083A JP 8769193 A JP8769193 A JP 8769193A JP 8769193 A JP8769193 A JP 8769193A JP H06303083 A JPH06303083 A JP H06303083A
- Authority
- JP
- Japan
- Prior art keywords
- acoustic wave
- surface acoustic
- interdigital
- piezoelectric substrate
- interdigital 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.)
- Pending
Links
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は、弾性表面波素子におけ
るインターディジタル形トランスジューサの構造に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of an interdigital transducer in a surface acoustic wave device.
【0002】[0002]
【従来の技術】弾性表面波素子は、圧電基板(又は非圧
電性基板に圧電性薄膜を蒸着した基板)上にアルミニウ
ム等の電極材料によりすだれ状電極を蒸着やホトエッチ
ングにより形成するものが一般的である。2. Description of the Related Art A surface acoustic wave device is generally one in which a comb-shaped electrode is formed by vapor deposition or photoetching on a piezoelectric substrate (or a substrate obtained by vapor-depositing a piezoelectric thin film on a non-piezoelectric substrate) using an electrode material such as aluminum. Target.
【0003】圧電基板は弾性表面波の伝搬手段となり、
すだれ状電極は圧電基板との組み合わせで電気−弾性波
のエネルギー変換を行うインターディジタル形トランス
ジューサ(IDT)になる。The piezoelectric substrate serves as a means for propagating surface acoustic waves,
The interdigital transducer serves as an interdigital transducer (IDT) that performs energy conversion of electro-acoustic waves in combination with a piezoelectric substrate.
【0004】この弾性表面波素子は、励振された表面波
を利用して共振子やフイルタとして使われる。This surface acoustic wave element is used as a resonator or a filter by utilizing the excited surface wave.
【0005】図2は、すだれ状電極例を示し、同図の
(a)にはシングル電極を持つ素子の斜視図を示し、
(b)にはダブル電極を持つ素子の斜視図を示す。FIG. 2 shows an example of a comb-shaped electrode, and FIG. 2 (a) is a perspective view of an element having a single electrode.
(B) shows a perspective view of an element having a double electrode.
【0006】[0006]
【発明が解決しようとする課題】従来の一般のすだれ状
電極を用いたフイルタでは、弾性表面波が両方向に伝搬
するため、6dbの挿入損失が発生する。また、伝搬の
両方向性と2次効果による反射のため、帯域内に大きな
リップルを発生する問題がある。In a conventional filter using a general interdigital transducer, a surface acoustic wave propagates in both directions, so that an insertion loss of 6 db occurs. Further, there is a problem that a large ripple is generated in the band due to bidirectionality of propagation and reflection due to the secondary effect.
【0007】これらの問題を解消するために、3トラン
スジューサ方式やマルチトランスジューサ方式等がフイ
ルタの構成方法として提案されている。また、トランス
ジューサそのものに一方向性を持たせるようにしたもの
が種々提案され、数種類の一方向性トランスジューサが
実用化されている。In order to solve these problems, a 3-transducer system, a multi-transducer system, etc. have been proposed as a method for constructing a filter. Various types of unidirectional transducers have been proposed, and several types of unidirectional transducers have been put into practical use.
【0008】図3は、一方向性のトランスジューサの電
極パターン構成例を示す。同図中、矢印は弾性表面波の
伝搬方向を示す。FIG. 3 shows an example of the electrode pattern configuration of a unidirectional transducer. In the figure, the arrow indicates the propagation direction of the surface acoustic wave.
【0009】これらの弾性表面波素子は、一方向性を得
ることができるが、電極パターン構造が複雑になり、高
周波のフイルタになるほどその設計・製造を難しくする
と共にコストアップになる。These surface acoustic wave devices can obtain unidirectionality, but the electrode pattern structure becomes complicated, and the higher the frequency of the filter, the more difficult it is to design and manufacture, and the cost increases.
【0010】本発明の目的は、すだれ状電極のパターン
構成を簡単にしながら一方向性を持たせる弾性表面波素
子を提供することにある。It is an object of the present invention to provide a surface acoustic wave device having a unidirectional property while simplifying the pattern configuration of the interdigital transducer.
【0011】[0011]
【課題を解決するための手段】本発明は、前記課題の解
決を図るため、圧電基板の表面にすだれ状電極を形成し
てインターディジタル形トランスジューサを構成する弾
性表面波素子において、前記圧電基板は弾性表面波の伝
搬方向に向かって同じ方向の傾斜面を持つ突起部を所定
の間隔で設け、前記すだれ状電極は前記突起部に電極膜
を蒸着又はホトエッチングによって形成し、弾性表面波
を一方向に伝搬させることを特徴とする。In order to solve the above-mentioned problems, the present invention provides a surface acoustic wave device in which interdigital transducers are formed by forming interdigital transducers on the surface of a piezoelectric substrate. Protrusions having inclined surfaces in the same direction toward the propagation direction of the surface acoustic wave are provided at a predetermined interval, and the interdigital electrode is formed by vapor-depositing or photo-etching an electrode film on the protrusion to generate a surface acoustic wave. It is characterized by propagating in the direction.
【0012】[0012]
【作用】弾性表面波の伝搬方向に対して傾斜面を持つす
だれ状電極を設けることにより、圧電基板の励振に方向
性を持たせ、弾性表面波の伝搬に方向性を持たせる。す
だれ状電極のパターンは両方向性の素子と同等にする。By providing the interdigital electrode having the inclined surface with respect to the propagation direction of the surface acoustic wave, the excitation of the piezoelectric substrate is made directional, and the propagation of the surface acoustic wave is made directional. The pattern of the interdigital electrodes is the same as that of the bidirectional element.
【0013】[0013]
【実施例】図1は、本発明の一実施例を示すインターデ
ィジタル形トランスジューサの断面図である。同図は、
図2の(a)に示すシングル電極と同じパターン構成に
なるトランスジューサの断面構造を示す。1 is a sectional view of an interdigital transducer showing an embodiment of the present invention. This figure shows
3 shows a cross-sectional structure of a transducer having the same pattern configuration as the single electrode shown in FIG.
【0014】圧電基板1は、水晶、タンタル酸リチウ
ム、ニオブ酸リチウム等の圧電性材料で構成され、すだ
れ状電極を形成する表面位置には弾性表面波の進行方向
(矢印で示す)に向かって同方向の傾斜面を持つ突起部
1aが形成される。The piezoelectric substrate 1 is made of a piezoelectric material such as quartz, lithium tantalate, lithium niobate, etc., and is directed toward the traveling direction of the surface acoustic wave (indicated by an arrow) at the surface position forming the interdigital transducer. The protrusion 1a having an inclined surface in the same direction is formed.
【0015】この各突起部1aを持つ圧電基板1は、例
えばエッチング(ドライエッチング、ウェットエッチン
グ)加工によって実現される。また、突起部1aの間隔
は伝搬させる弾性表面波の周波数に応じて決定される。The piezoelectric substrate 1 having the protrusions 1a is realized by, for example, etching (dry etching, wet etching) processing. Further, the interval between the protrusions 1a is determined according to the frequency of the surface acoustic wave to be propagated.
【0016】各突起部1aの表面にはアルミニウムの蒸
着ですだれ状電極の電極膜2a、2bが蒸着又はホトエ
ッチングによって形成される。Electrode films 2a and 2b, which are interdigital electrodes, are formed on the surface of each protrusion 1a by vapor deposition of aluminum by vapor deposition or photoetching.
【0017】本実施例の弾性表面波素子において、すだ
れ状電極の電極膜2a、2bには励振電源3からの励振
に対して所定周波数の弾性表面波を伝搬させる。この伝
搬には、電極膜2a、2bによる圧電基板1の励振が突
起部1aの存在により方向性を持つため、一方向(矢印
方向)になる。In the surface acoustic wave device of this embodiment, surface acoustic waves of a predetermined frequency are propagated through the electrode films 2a, 2b of the interdigital transducers in response to the excitation from the excitation power source 3. For this propagation, the excitation of the piezoelectric substrate 1 by the electrode films 2a and 2b has a directional property due to the presence of the protrusions 1a, and therefore is in one direction (arrow direction).
【0018】この一方向伝搬により、従来の両方向伝搬
による挿入損失が無くなり、また反射によるリップルの
発生を抑えることができる。しかも、電極構造として
は、従来のシングル電極と同じパターン構成になり、そ
の形成を容易にする。By this one-way propagation, the insertion loss due to the conventional two-way propagation is eliminated, and the generation of ripple due to reflection can be suppressed. Moreover, the electrode structure has the same pattern configuration as that of the conventional single electrode, which facilitates its formation.
【0019】なお、実施例において、圧電基板の突起部
の断面構造は一定の傾斜にするに限らず、断面が曲線に
なる傾斜を持つ構造にして同等の作用効果を奏する。In the embodiment, the sectional structure of the protrusions of the piezoelectric substrate is not limited to a constant inclination, but a structure having an inclination in which the cross section has a curved shape is obtained, and the same effect is obtained.
【0020】また、突起部の間隔は素子の使用目的によ
って一定のものの外に所定比で増減する構成にされる。
さらに、すだれ状電極のパターンも適宜設計変更され
る。Further, the interval between the projections is not limited to a constant value depending on the purpose of use of the element, but is increased or decreased at a predetermined ratio.
Further, the design of the interdigital electrode may be changed as appropriate.
【0021】[0021]
【発明の効果】以上のとおり、本発明によれば、弾性表
面波の伝搬方向に対して傾斜面を持つすだれ状電極を設
けることにより弾性表面波の伝搬に方向性を持たせるよ
うにしたため、すだれ状電極のパターン構成を両方向性
インターディジタル形トランスジューサと同じの簡単な
構成になり、しかも一方向性を持つことで6dbの挿入
損失を無くすと共に反射によるリップルを低減できる効
果がある。As described above, according to the present invention, since the interdigital transducer having the inclined surface with respect to the propagation direction of the surface acoustic wave is provided, the propagation of the surface acoustic wave is made directional. The interdigital transducer pattern has the same simple structure as that of the bidirectional interdigital transducer, and by having unidirectionality, the insertion loss of 6 db can be eliminated and the ripple due to reflection can be reduced.
【図1】本発明の一実施例を示す素子の断面図。FIG. 1 is a sectional view of an element showing an embodiment of the present invention.
【図2】従来のインターディジタル形トランスジューサ
の構成例。FIG. 2 shows a configuration example of a conventional interdigital transducer.
【図3】従来の一方向性を持つ素子の電極パターン構成
例。FIG. 3 is an example of an electrode pattern configuration of a conventional unidirectional device.
1…圧電基板 1a…突起部 2a、2b…すだれ状電極の電極膜 3…励振電源 DESCRIPTION OF SYMBOLS 1 ... Piezoelectric substrate 1a ... Protrusions 2a, 2b ... Electrode film of interdigital electrodes 3 ... Excitation power supply
Claims (1)
てインターディジタル形トランスジューサを構成する弾
性表面波素子において、前記圧電基板は弾性表面波の伝
搬方向に向かって同じ方向の傾斜面を持つ突起部を所定
の間隔で設け、前記すだれ状電極は前記突起部に電極膜
を蒸着又はホトエッチングによって形成し、弾性表面波
を一方向に伝搬させることを特徴とする弾性表面波素
子。1. In a surface acoustic wave device in which an interdigital transducer is formed by forming interdigital transducers on the surface of a piezoelectric substrate, the piezoelectric substrate has an inclined surface in the same direction as the propagation direction of the surface acoustic wave. A surface acoustic wave device, characterized in that projections are provided at predetermined intervals, and that the interdigital transducer has an electrode film formed on the projections by vapor deposition or photoetching to propagate a surface acoustic wave in one direction.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8769193A JPH06303083A (en) | 1993-04-15 | 1993-04-15 | Surface acoustic wave element |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8769193A JPH06303083A (en) | 1993-04-15 | 1993-04-15 | Surface acoustic wave element |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH06303083A true JPH06303083A (en) | 1994-10-28 |
Family
ID=13921958
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP8769193A Pending JPH06303083A (en) | 1993-04-15 | 1993-04-15 | Surface acoustic wave element |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH06303083A (en) |
-
1993
- 1993-04-15 JP JP8769193A patent/JPH06303083A/en active Pending
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