JPH038123B2 - - Google Patents
Info
- Publication number
- JPH038123B2 JPH038123B2 JP55045833A JP4583380A JPH038123B2 JP H038123 B2 JPH038123 B2 JP H038123B2 JP 55045833 A JP55045833 A JP 55045833A JP 4583380 A JP4583380 A JP 4583380A JP H038123 B2 JPH038123 B2 JP H038123B2
- Authority
- JP
- Japan
- Prior art keywords
- electrode
- electrode finger
- present
- bandwidth
- finger
- 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
- 230000006866 deterioration Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004904 shortening Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 238000010897 surface acoustic wave method Methods 0.000 description 2
- 238000004519 manufacturing process Methods 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
- H03H9/46—Filters
- H03H9/64—Filters using surface acoustic waves
- H03H9/6423—Means for obtaining a particular transfer characteristic
Landscapes
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Description
【発明の詳細な説明】 本発明は表面波装置に関する。[Detailed description of the invention] The present invention relates to a surface wave device.
本発明は、インターデイジタル電極の最外側の
電極指を短くすると共に、その短くした電極指の
延長上に、電極指と分離された浮き電極指を形成
したことを特徴とする、表面波装置である。 The present invention is a surface wave device characterized in that the outermost electrode finger of an interdigital electrode is shortened, and a floating electrode finger separated from the electrode finger is formed on an extension of the shortened electrode finger. be.
表面波装置は、通常、フイルタ、遅延線に用い
られ、圧電性基板上に対のくし歯状電極を相互に
差し込んでなる入出力インターデイジタル電極が
形成されたものである。表面波装置の通過帯域特
性は主として中心周波数0と対数Ｎで決定され、
その帯域幅は20／Ｎで決まる。対数Ｎは電極指
の数に応じて決まり、0.5，1.0，1.5…というよう
に非連続的な数となり、帯域幅は飛び飛びの非連
続的な値のものしか実現できなかつた。したがつ
て、希望の帯域幅が例えば20／Ｎと20／（Ｎ−
0.5）の間に入つてしまうことがしばしばあり、
希望帯域幅に合致した表面波装置を得ることが困
難であつた。なお、中心周波数0はインターデイ
ジタル電極の隣接する電極指の中心間距離で決ま
る。 Surface wave devices are usually used in filters and delay lines, and have input/output interdigital electrodes formed by interdigitating pairs of comb-like electrodes on a piezoelectric substrate. The passband characteristics of a surface wave device are mainly determined by the center frequency 0 and the logarithm N,
Its bandwidth is determined by 2 0 /N. The logarithm N is determined according to the number of electrode fingers, and is a discontinuous number such as 0.5, 1.0, 1.5, etc., and the bandwidth can only be achieved with discontinuous values. Therefore, if the desired bandwidth is, for example, 2 0 /N and 2 0 /(N−
0.5),
It has been difficult to obtain a surface wave device that meets the desired bandwidth. Note that the center frequency 0 is determined by the distance between the centers of adjacent electrode fingers of the interdigital electrodes.
本発明は、上述した従来の技術状況に鑑みてな
されたもので、対数Ｎで決まる飛び飛びの通過帯
域幅の間に位置する帯域幅も任意にかつ容易に得
ることができ、しかも特性劣化を極力抑えるよう
にした表面波装置を提供することを目的とする。 The present invention has been made in view of the above-mentioned conventional technical situation, and it is possible to arbitrarily and easily obtain a bandwidth located between discrete passband widths determined by the logarithm N, and to minimize characteristic deterioration. It is an object of the present invention to provide a surface wave device that suppresses the noise.
以下、本発明の一実施例を図面を参照しつつ詳
述する。 Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.
第１図において、２は圧電性基板１上に形成さ
れたインターデイジタル電極で、一対のくし歯電
極３，４が相互に差し込まれて構成されている。
電極２の最外側の電極指５が指長さ方向の途中箇
所６で切断され、有効長が所定長さより短くなる
ように構成されている。このように最外側の電極
指５を短くすることにより、得られる帯域幅を広
くすることができる。具体的には、電極指５を短
くする前の状態での帯域幅と電極指５を取り除い
た状態（対数を少なくした状態）での帯域幅との
間に位置する帯域幅が得られる。第２図は本発明
と従来例の通過帯域特性を示し、曲線Ａが本発明
によるもので、対数Ｎ＝4.5の正規型電極の最外
側の電極指を約半分に短くしたものであり、曲線
Ｂが対数Ｎ＝４の従来正規型電極によるものであ
り、曲線Ｃが対数Ｎ＝4.5の従来正規型電極によ
るものである。同図の特性からも本発明の効果は
明らかであろう。特に、本発明は、テレビジヨン
受像機の映像中間周波段フイルタとして用いた場
合、通過帯域の両側の減衰極を、規格で定まつて
いる隣接チヤンネル映像搬送周波数や隣接チヤン
ネル音声搬送周波数に合致させることが容易とな
る。 In FIG. 1, reference numeral 2 denotes an interdigital electrode formed on a piezoelectric substrate 1, and is composed of a pair of comb-shaped electrodes 3 and 4 inserted into each other.
The outermost electrode finger 5 of the electrode 2 is cut at a halfway point 6 in the finger length direction, so that the effective length is shorter than a predetermined length. By shortening the outermost electrode fingers 5 in this manner, the obtained bandwidth can be widened. Specifically, a bandwidth is obtained that is located between the bandwidth before the electrode fingers 5 are shortened and the bandwidth when the electrode fingers 5 are removed (the logarithm is reduced). Figure 2 shows the passband characteristics of the present invention and the conventional example, where curve A is according to the present invention and is obtained by shortening the outermost electrode finger of a normal type electrode with logarithm N = 4.5 to about half; Curve B is based on a conventional normal type electrode with a logarithm of N=4, and curve C is based on a conventional normal type electrode with a logarithm of N=4.5. The effects of the present invention will be clear from the characteristics shown in the figure. In particular, when the present invention is used as a video intermediate frequency stage filter for a television receiver, the attenuation poles on both sides of the passband match the adjacent channel video carrier frequency and adjacent channel audio carrier frequency defined by the standard. This makes it easier.
上記実施例において、電極指５の切断された残
りの部分５ａは電極指とは電気的に絶縁された浮
き電極としてそのまま残され、ダミーの電極指と
して機能させている。また、短くする電極指は電
極指５とは反対側の最外側のものとしてもよい。
インターデイジタル電極を表面波伝播方向に複数
に分割し、分割された部分電極を伝播方向に沿つ
て電気的に直列に接続するようにした分割型電極
にも適用でき、特にこの場合は、従来の電極では
帯域幅を合致させることが非常に難しいので、得
られる効果がより一層大きくなる。さらに、本発
明は表面波装置の製造後に帯域特性を微調整する
手段としても使うことができる。 In the above embodiment, the cut remaining portion 5a of the electrode finger 5 is left as it is as a floating electrode electrically insulated from the electrode finger, and functions as a dummy electrode finger. Further, the electrode finger to be shortened may be the outermost one on the opposite side from the electrode finger 5.
It can also be applied to split-type electrodes in which the interdigital electrode is divided into multiple parts in the surface wave propagation direction and the divided partial electrodes are electrically connected in series along the propagation direction. Since it is very difficult to match the bandwidth of electrodes, the effect obtained is even greater. Furthermore, the present invention can be used as a means for finely adjusting the band characteristics after manufacturing a surface acoustic wave device.
本発明は、以上説明したように、インターデイ
ジタル電極の最外側の電極指を所定長さより短
く、かつ浮き電極を設けるという、きわめて簡単
な手段により、特性劣化を招くことなく、通過帯
域幅を任意に設定もしくは微調整でき、希望帯域
幅に容易に合致させることができるという効果を
有している。しかも、上記最外側の電極指の延長
上に、電極指と分離されて浮き電極指を形成して
いるため、相手方の重み付け電極の交差幅の大き
い電極部で励振された波を確実に受信することが
でき、従つて特性の劣化を極力抑えることができ
る。のみならず、この浮き電極指により、電極の
有無に基づく波面の歪みを是正することも可能と
なる。 As explained above, the present invention uses extremely simple means of making the outermost electrode finger of the interdigital electrode shorter than a predetermined length and providing a floating electrode, so that the passband width can be adjusted arbitrarily without causing characteristic deterioration. It has the advantage that it can be set or finely adjusted to match the desired bandwidth easily. Moreover, since the floating electrode finger is formed on the extension of the outermost electrode finger and is separated from the electrode finger, it is possible to reliably receive the waves excited by the electrode part with a large crossing width of the other weighting electrode. Therefore, deterioration of characteristics can be suppressed as much as possible. In addition, the floating electrode fingers also make it possible to correct wavefront distortion caused by the presence or absence of electrodes.
第１図は本発明による表面波装置の一実施例を
示す図、第２図は通過帯域特性を示す図である。
２はインターデイジタル電極、５は最外側電極
指、５ａは浮き電極指である。
FIG. 1 is a diagram showing an embodiment of a surface acoustic wave device according to the present invention, and FIG. 2 is a diagram showing passband characteristics. 2 is an interdigital electrode, 5 is an outermost electrode finger, and 5a is a floating electrode finger.
Claims (1)
極指を短くするとともに、その短くした電極指の
延長上に、電極指と分離された浮き電極指を形成
したことを特徴とする表面波装置。1. A surface wave device characterized in that the outermost electrode finger of a regular interdigital electrode is shortened, and a floating electrode finger separated from the electrode finger is formed on an extension of the shortened electrode finger.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4583380A JPS56141614A (en) | 1980-04-07 | 1980-04-07 | Surface wave equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4583380A JPS56141614A (en) | 1980-04-07 | 1980-04-07 | Surface wave equipment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS56141614A JPS56141614A (en) | 1981-11-05 |
| JPH038123B2 true JPH038123B2 (en) | 1991-02-05 |
Family
ID=12730219
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4583380A Granted JPS56141614A (en) | 1980-04-07 | 1980-04-07 | Surface wave equipment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS56141614A (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5310946A (en) * | 1976-07-17 | 1978-01-31 | Matsushita Electric Ind Co Ltd | Elastic surface wave filter |
-
1980
- 1980-04-07 JP JP4583380A patent/JPS56141614A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5310946A (en) * | 1976-07-17 | 1978-01-31 | Matsushita Electric Ind Co Ltd | Elastic surface wave filter |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS56141614A (en) | 1981-11-05 |
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