JPS6313510A - Surface acoustic wave filter - Google Patents
Surface acoustic wave filterInfo
- Publication number
- JPS6313510A JPS6313510A JP15602786A JP15602786A JPS6313510A JP S6313510 A JPS6313510 A JP S6313510A JP 15602786 A JP15602786 A JP 15602786A JP 15602786 A JP15602786 A JP 15602786A JP S6313510 A JPS6313510 A JP S6313510A
- Authority
- JP
- Japan
- Prior art keywords
- electrode
- fingers
- electrodes
- surface acoustic
- common
- 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.)
- Granted
Links
- 238000010897 surface acoustic wave method Methods 0.000 title claims abstract description 19
- 239000000758 substrate Substances 0.000 claims description 5
- 239000007787 solid Substances 0.000 claims description 2
- 239000000463 material Substances 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 5
- 230000002457 bidirectional effect Effects 0.000 description 4
- 230000005284 excitation Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000004904 shortening Methods 0.000 description 2
- 229910003327 LiNbO3 Inorganic materials 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、低損失化に好適な、一方向性トランスジュー
サを備えた弾性表面波フィルタの構造に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a surface acoustic wave filter equipped with a unidirectional transducer, which is suitable for reducing loss.
従来、一方向性トランスジューサを備えた弾性表面波フ
ィルタは、特開昭５１−１３８３６２号公報に開示され
ている様に、第１のすだれ状電極群を形成する第１電極
と共通ミアンダ電極、第２のすだれ状電極群を形成する
第２電極と共通ミアンダ電極それぞれの間をｎ±１／４
波長としくｎは任意の整数）、更に第１．第２電極群間
に９０度移相器を接続して電気的な位相差を与え、一方
向のみに弾性表面波を伝搬させるようにしたトランスジ
ューサを用いて、双方向に表面波が励振されるために生
ずる変換損失（３ｄＢ）を改善していた。Conventionally, a surface acoustic wave filter equipped with a unidirectional transducer includes a first electrode forming a first interdigital electrode group, a common meander electrode, and a common meander electrode, as disclosed in Japanese Patent Application Laid-Open No. 51-138362. The distance between the second electrode and the common meandering electrode forming the two interdigital electrode groups is n±1/4.
(where n is an arbitrary integer), and the first . Surface waves are excited in both directions using a transducer in which a 90-degree phase shifter is connected between the second electrode group to provide an electrical phase difference and allow surface acoustic waves to propagate in only one direction. The conversion loss (3 dB) caused by this was improved.
しかし、上記従来の技術は、第２図に示すように、第１
電極６と共通ミアンダ電極８による第１電極群の励振源
である交差部分１７と、第２電極７と共通ミアンダ電極
８による第２電極群の励振源である交差部分１８が、同
一伝搬路上に存在しないため、不要交差部分１９．２０
によシ一方向性の条件を外れて双方向に伝搬する表面波
が発生し、損失が増加するという問題があった。However, as shown in FIG.
An intersection portion 17 that is an excitation source for the first electrode group formed by the electrode 6 and the common meander electrode 8, and an intersection portion 18 that is an excitation source for the second electrode group formed by the second electrode 7 and the common meander electrode 8 are on the same propagation path. Unnecessary intersection 19.20 because it does not exist
However, there is a problem in that surface waves that propagate in both directions deviate from the unidirectional condition, resulting in increased loss.
本発明は上記従来の一方向性トランスジューサを用いた
弾性表面波フィルタの問題点を解決し、低損失にした弾
性表面波フィルタを提供することを目的とする。An object of the present invention is to solve the problems of the conventional surface acoustic wave filter using a unidirectional transducer, and to provide a surface acoustic wave filter with low loss.
上記問題点を解決するために本発明においては、第１す
だれ状電極群と共通ミアンダ電極との電極指交差部分と
、ＷｆＩ２すだれ状電極群と共通ミアンダ電極との電極
指交差部分とが、孤立突出した部分なく一つの伝搬路を
形成するようにした。In order to solve the above problems, in the present invention, the electrode finger crossing portion between the first interdigital electrode group and the common meander electrode, and the electrode finger crossing portion between the WfI2 interdigital electrode group and the common meander electrode are isolated. A single propagation path is formed without any protruding parts.
但し、すだれ状電極群と共通ミアンダ電極との電極指交
差部分は、所望の帯域内周波数における波長をλ０とし
て、＋＊接対向する電極指の間隔を。However, at the intersecting portion of the interdigital electrode group and the common meandering electrode, the wavelength at the desired in-band frequency is λ0, and the distance between the electrode fingers facing each other is +*.
ソリッド形電極指の場合はぼλ０／４以内、スプリット
形電極指の場合はぼλ、Ｉ／８以内に設定してあ・ ３
・
る。For solid type electrode fingers, set it within approximately λ0/4, and for split type electrode fingers, set it within approximately λ, I/8.
・Ru.
また、交差幅重み付は電極のように、電極指交差部分の
長さく即ち交差幅）を徐々に変化させる場合は、この緩
やかな変化から外れた孤立突出部分がなければ良い。ス
プリット形電極指の場合、本発明を適用する際は、２本
１組の電極指の長さを上記原則に従って変化させる。Furthermore, when the cross width weighting is used to gradually change the length of the intersecting portion of the electrode fingers (i.e., the cross width), as in the case of electrodes, it is sufficient as long as there is no isolated protruding portion that deviates from this gradual change. In the case of split-type electrode fingers, when applying the present invention, the length of each pair of electrode fingers is changed according to the above principle.
第１電極と共通ミアンダ電極によ）形成される交差部分
と、第２電極と共通ミアンダ電極により形成される交差
部分とが、孤立突出した不要部分なく一つの伝搬路を形
成していれば、第１すだれ状電極と第２すだれ状電極で
発生する弾性表面波は、すべて相互作用を起こし、一方
向に弾性表面波を発生させることが出来る。If the intersection formed by the first electrode and the common meander electrode and the intersection formed by the second electrode and the common meander electrode form one propagation path without any isolated and protruding unnecessary parts, then The surface acoustic waves generated by the first interdigital electrode and the second interdigital electrode all interact to generate surface acoustic waves in one direction.
また、スプリット電極の場合、順方向で見た励振源が略
Ｖ／ ２ ｆｏ（ｆｏ：ピッチによって決まる中心周波
数、Ｖ：実効表面波速度）の間隔で並び、励振源の抜け
を無くすることは、上記第１．第２すだれ状電極間のミ
アンダ電極の本数を１本と３本４ ・
の繰シ返しで形成することＫよシ実現できる。この電極
では、１本のミアンダ電極からなる部分は、電極幅がλ
ｏ／８程度であるため、電極を細めても効果が少ない。In addition, in the case of split electrodes, the excitation sources viewed in the forward direction are lined up at an interval of approximately V/2 fo (fo: center frequency determined by pitch, V: effective surface wave velocity), and it is difficult to eliminate omission of excitation sources. , above No. 1. The number of meander electrodes between the second interdigital electrodes can be repeatedly formed in the following manner: 1 and 3. In this electrode, the part consisting of one meandering electrode has an electrode width of λ
Since it is about o/8, there is little effect even if the electrode is made thinner.
そこで１本のミアンダ電極に近い第１．第２電極を短く
し、ミアンダ電極３本の部分では逆にミアンダ電極側を
短くすることにより、交差部分を同一伝搬路上に設ける
ことができる。Therefore, the first electrode near one meander electrode. By shortening the second electrode and conversely shortening the meander electrode side in a portion with three meander electrodes, the crossing portions can be provided on the same propagation path.
第１図は本発明の第１実施例図である。圧電性基板４と
してＬｉＮｂＯ３基板を用い、スプリット形として第１
電極（１−１，１−Ｎ第２電極（２−１゜２−２）共通
ミアンダ電極（３−１，３−２）を形成し。FIG. 1 is a diagram showing a first embodiment of the present invention. A LiNbO3 substrate is used as the piezoelectric substrate 4, and the first
Electrodes (1-1, 1-N second electrodes (2-1, 2-2) and common meander electrodes (3-1, 3-2) are formed.
一方向性の条件を満足する９０度移相器（５−ｉ。A 90 degree phase shifter (5-i) that satisfies the unidirectional condition.
５−２）を接続し、正規型の一方向性トランスジューサ
を形成する。交差幅Ｗ＝１０００μｍとした。伺、交差
幅とは電極交差部分の長さを云う。共通ミアンダ電極指
が１本の個所（１５８〜１５ｅ）と其の両隣の電極の電
極指の交差幅、及び、共通ミアンダ電極指が３木の個所
（１８〜１６０）と其の両隣の電極の電極指の交差幅が
同一伝搬路上に来るように。5-2) to form a regular unidirectional transducer. The intersection width W was set to 1000 μm. The crossing width refers to the length of the electrode crossing portion. The intersecting width of the electrode fingers of a point with one common meander electrode finger (158 to 15e) and the electrodes on both sides of it, and the intersection width of the electrode fingers of a point with three common meander electrode fingers (18 to 160) and the electrodes on both sides thereof. Make sure that the intersecting widths of the electrode fingers are on the same propagation path.
共通ミアンダ電極指が１本の個所では其の両隣のスプリ
ット電極の電極指のうちの１本を途中で削除し、もう１
本の電極指に接続する。共通ミアンダ電極指が３本の個
所では、共通ミアンダ電極を第１．第２電極側で夫々２
本ずつ途中で削除する。In a place where there is one common meander electrode finger, one of the electrode fingers of the split electrodes on both sides of it is deleted midway, and the other one is removed.
Connect to the book's electrode finger. In locations where there are three common meander electrode fingers, the common meander electrode is placed first. 2 each on the second electrode side
Delete one book at a time.
本実施例は、正規型のスプリット形一方向性トランスジ
ューサを用いた弾性表面波フィルタで、同一伝搬路上に
交差部分があるので双方向伝搬による変換損失が改善で
きる。伺、第１図は入出力の二つの電極を示したもので
ある。This embodiment is a surface acoustic wave filter using a regular split type unidirectional transducer, and since there is an intersection on the same propagation path, conversion loss due to bidirectional propagation can be improved. Figure 1 shows two input and output electrodes.
第３図は本発明の第２実施例を示す。本図は入出力電極
のうちの何れか一方を示し、圧電性基板の上に電極指を
スプリット形にした第１電極９゜第２電極１０．共通ミ
アンダ電極１１が配設してあり、且つ交差幅方向に重み
付けしである。交差幅方向に重み付けしたトランスジュ
ーサは第１実施例と同様に第１電極、第２電極、共通ミ
アンダ電極の形状を変えている。この第２実施例の如く
すれば、交差幅方向に重み付けした場合でも、前述した
不要交差部での双方向伝搬による変換損失全改善できる
。FIG. 3 shows a second embodiment of the invention. This figure shows one of the input and output electrodes, the first electrode 9°, the second electrode 10. A common meander electrode 11 is provided and weighted in the cross width direction. In the transducer weighted in the cross-width direction, the shapes of the first electrode, the second electrode, and the common meander electrode are changed as in the first embodiment. According to the second embodiment, even when weighting is applied in the cross width direction, the conversion loss due to the bidirectional propagation at the unnecessary cross section described above can be completely improved.
第４図は本発明の第３実施例を示す。本図は入出力電極
のうち何れか一方を示しており、圧電性基板の上に夫り
電極指をスプリット形にした第１電極１２、第２電極１
３、共通ミアンダ電極１４が配設してあり、目、つ、交
差幅方向に重み付けをしである。共通ミアンダ電極の電
極指が３本の個所の電極指のうち、外側の２本の電極指
が両側の電極の電極指と上下対になるように接続した。FIG. 4 shows a third embodiment of the invention. This figure shows one of the input and output electrodes, the first electrode 12 and the second electrode 1 having split electrode fingers on the piezoelectric substrate.
3. A common meander electrode 14 is provided, which is weighted in the cross width direction. Of the three electrode fingers of the common meander electrode, the outer two electrode fingers were connected to the electrode fingers of the electrodes on both sides in a vertical pair.
本実施例によれば、交差幅方向に重み付けした場合でも
、それ以外の交差幅による双方向伝搬損失が改善できる
と共に、弾性表面波伝搬方向での共通ミアンダ電極の一
部が省略されている個所が多く。According to this embodiment, even when weighting is applied in the intersection width direction, bidirectional propagation loss due to other intersection widths can be improved, and a portion of the common meander electrode in the surface acoustic wave propagation direction is omitted. There are many.
交差幅方向で電極のメタライズされた個所と、されてい
ない個所の比が略一様となるため１弾性表面波の位相も
略一様となり、特性の劣化が少ない。Since the ratio of the metalized portions of the electrodes to the non-metalized portions in the cross width direction is approximately uniform, the phase of one surface acoustic wave is also approximately uniform, and there is little deterioration in characteristics.
以上説明したように本発明によれば、電極指の不要交差
部分における双方向伝搬損失を除去した一方向性トラン
スジューサを用いることにより低損失化した弾性表面波
フィルタが得られる。As described above, according to the present invention, a surface acoustic wave filter with reduced loss can be obtained by using a unidirectional transducer that eliminates bidirectional propagation loss at unnecessary intersections of electrode fingers.
第１図は本発明第１実施例の模式図、第２図は従来の一
方向性トランスジューサの模式図、第３図は本発明第２
実施例の一方向性トランスジューサの模式図、第４図は
本発明第３実施例の一方向性トランスジューサの模式図
である。
１−１．１−２．６，９．１２・・・第１電極２−１．
２−２．７，１０．１３・・・第２電極３−１．３−２
．８，１１．１４・・・共通ミアンダ電極４・・・圧電
性基板
５−１．５−２・・・移相器
１５＆〜１５ｅ・・・共通ミアンダ電極の１本の個所Ｉ
Ｓａ〜１６ｏ・・・共通ミアンダ電極の３本の個所１７
・・・第１電極***差部
１８・・・第２電極***差部Fig. 1 is a schematic diagram of the first embodiment of the present invention, Fig. 2 is a schematic diagram of a conventional unidirectional transducer, and Fig. 3 is a schematic diagram of the conventional unidirectional transducer.
FIG. 4 is a schematic diagram of a unidirectional transducer according to a third embodiment of the present invention. 1-1.1-2.6, 9.12...first electrode 2-1.
2-2.7, 10.13... Second electrode 3-1.3-2
．． 8,11.14...Common meander electrode 4...Piezoelectric substrate 5-1.5-2...Phase shifter 15&~15e...One location I of common meander electrode
Sa~16o...Three points 17 of common meander electrode
...First electrode group intersection 18...Second electrode group intersection
Claims (1)
れ状電極群を設け、これらのすだれ状電極群に、電気的
位相差のある信号を与えて、弾性表面波エネルギーが一
方向へ逆方向よりも多く伝搬するようにした一方向性ト
ランスジューサを用いた弾性表面波フィルタにおいて、
所望の帯域内周波数における波長をλ＿０として、上記
第１、第２のすだれ状電極群の電極指と隣接対向する共
通ミアンダ電極との間隔を、ソリッド形電極指の場合に
略λ＿０／４以内、スプリット形電極指の場合に略λ＿
０／８以内に設定した電極指交差部分が、孤立突出した
不要部分なく一つの伝搬路を形成している一方向性トラ
ンスジューサを使用していることを特徴とする弾性表面
波フィルタ。 ２、第１、第２すだれ状電極群の同一電極に接続した電
極指が、夫々２本１組に形成したスプリット形電極指よ
りなる一方向性トランスジューサを用いた弾性表面波フ
ィルタにおいて、１本の共通ミアンダ電極と、これと隣
接する第１、第２すだれ状電極群電極指からなる組合せ
、及び、３本の共通ミアンダ電極と、これと隣接する第
１、第２すだれ状電極群電極指の組合せからなるグルー
プが少なくとも一つ以上存在し、且つ、第１又は第２電
極群電極指と共通ミアンダ電極との間隔が略λ＿０／８
以内に設定されている電極指交差部分が同一伝搬路上に
あるように、共通ミアンダ電極が、本の個所の両隣の第
１、第２電極群電極指を、交差部分が所望長となるまで
短縮して同電極の他の１本の電極指に接続し、更に共通
ミアンダ電極が３本連続隣接する個所では、第１、第２
電極群電極指と隣接する共通ミアンダ電極を所望長とな
るまで短縮した一方向性トランスジューサを用いた特許
請求の範囲第１項記載の弾性表面波フィルタ。[Claims] 1. First and second interdigital electrode groups are provided on a surface acoustic wave substrate including a piezoelectric material, and signals having an electrical phase difference are applied to these interdigital electrode groups, In a surface acoustic wave filter using a unidirectional transducer in which surface acoustic wave energy propagates more in one direction than in the opposite direction,
Assuming that the wavelength at the desired in-band frequency is λ_0, the interval between the electrode fingers of the first and second interdigital electrode groups and the adjacent and opposing common meander electrode is approximately within λ_0/4 in the case of solid electrode fingers; Approximately λ_ in the case of split-type electrode fingers
A surface acoustic wave filter characterized in that a unidirectional transducer is used in which the intersecting portions of electrode fingers set within 0/8 form one propagation path without isolated and protruding unnecessary portions. 2. In a surface acoustic wave filter using a unidirectional transducer consisting of split-type electrode fingers, each of which is formed into a set of two electrode fingers connected to the same electrode of the first and second interdigital electrode groups, one A combination consisting of a common meander electrode and adjacent first and second interdigital electrode group electrode fingers, and three common meander electrodes and adjacent first and second interdigital electrode group electrode fingers. There is at least one group consisting of a combination of the above, and the distance between the first or second electrode group electrode finger and the common meander electrode is approximately λ_0/8.
The common meander electrode shortens the electrode fingers of the first and second electrode groups on both sides of the book part until the crossing part reaches the desired length so that the crossing parts of the electrode fingers that are set within the same distance are on the same propagation path. and connects to another electrode finger of the same electrode, and furthermore, in the place where three common meander electrodes are adjacent in succession, the first and second
The surface acoustic wave filter according to claim 1, which uses a unidirectional transducer in which a common meander electrode adjacent to the electrode group electrode finger is shortened to a desired length.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61156027A JP2619364B2 (en) | 1986-07-04 | 1986-07-04 | Surface acoustic wave filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61156027A JP2619364B2 (en) | 1986-07-04 | 1986-07-04 | Surface acoustic wave filter |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7500295A Division JPH07263994A (en) | 1995-03-31 | 1995-03-31 | Surface acoustic wave filter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6313510A true JPS6313510A (en) | 1988-01-20 |
| JP2619364B2 JP2619364B2 (en) | 1997-06-11 |
Family
ID=15618709
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61156027A Expired - Lifetime JP2619364B2 (en) | 1986-07-04 | 1986-07-04 | Surface acoustic wave filter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2619364B2 (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56157830A (en) * | 1980-05-08 | 1981-12-05 | Toshiba Corp | Laser machining apparatus |
| JPS5859611A (en) * | 1981-10-05 | 1983-04-08 | Matsushita Electric Ind Co Ltd | Digital type sound effect device |
-
1986
- 1986-07-04 JP JP61156027A patent/JP2619364B2/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56157830A (en) * | 1980-05-08 | 1981-12-05 | Toshiba Corp | Laser machining apparatus |
| JPS5859611A (en) * | 1981-10-05 | 1983-04-08 | Matsushita Electric Ind Co Ltd | Digital type sound effect device |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2619364B2 (en) | 1997-06-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EXPY | Cancellation because of completion of term |