JPS6138647B2 - - Google Patents
Info
- Publication number
- JPS6138647B2 JPS6138647B2 JP5451378A JP5451378A JPS6138647B2 JP S6138647 B2 JPS6138647 B2 JP S6138647B2 JP 5451378 A JP5451378 A JP 5451378A JP 5451378 A JP5451378 A JP 5451378A JP S6138647 B2 JPS6138647 B2 JP S6138647B2
- Authority
- JP
- Japan
- Prior art keywords
- electrode
- surface acoustic
- acoustic wave
- electrodes
- 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
Links
- 238000010897 surface acoustic wave method Methods 0.000 claims description 21
- 230000001902 propagating effect Effects 0.000 claims description 4
- 238000010586 diagram Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 230000002123 temporal effect Effects 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
- H03H9/02818—Means for compensation or elimination of undesirable effects
- H03H9/02842—Means for compensation or elimination of undesirable effects of reflections
-
- 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
- H03H9/14544—Transducers of particular shape or position
- H03H9/14552—Transducers of particular shape or position comprising split fingers
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、電極内の不要反射波を低減した弾性
表面波装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface acoustic wave device that reduces unnecessary reflected waves within electrodes.
弾性表面波フイルタにおける櫛形電極の構造と
しては、電極幅，電極間スペースが共に1/8波長
のダブルフインガ構造（Ａ―J.De Vries et al.
IEEE.U.S Symposium 353（1972））に作成する
と電極反射を防止出来ることが知られている。 The structure of the comb-shaped electrode in a surface acoustic wave filter is a double finger structure in which both the electrode width and the interelectrode space are 1/8 wavelength (A-J. De Vries et al.
IEEE.US Symposium 353 (1972)) is known to prevent electrode reflection.
又、弾性表面波を伝播方向に対し垂直な波面を
有する平面波として伝播させるために、補助電極
としてのダミー電極（米国特許第369936号参照）
を使用することが効果的であることが知られてい
る。 In addition, in order to propagate the surface acoustic wave as a plane wave with a wavefront perpendicular to the propagation direction, a dummy electrode (see US Pat. No. 369,936) is used as an auxiliary electrode.
It is known to be effective to use
しかし一般に、複雑な非対称の周波数特性を有
する弾性表面波フイルタを作成するためには、電
極交差幅、電極幅、電極スペースをそれぞれ所定
値に設定することが必要である。 However, in general, in order to create a surface acoustic wave filter having complex asymmetric frequency characteristics, it is necessary to set each of the electrode crossing width, electrode width, and electrode space to predetermined values.
第１図は従来使用されているダブルフインガ構
造でダミー電極を有する重み付電極の構造を示す
図である。 FIG. 1 is a diagram showing the structure of a conventionally used weighted electrode having a double finger structure and a dummy electrode.
従来のものは、図に示すように最大交差幅を有
する電極主要部１の両側に存在するダミー電極２
からの電極内不要反射波３が発生し、これが実用
上は大きな問題となる。 In the conventional type, dummy electrodes 2 exist on both sides of the electrode main part 1 having the maximum crossing width as shown in the figure.
Unnecessary reflected waves 3 within the electrode are generated, which poses a big problem in practice.
つまり、この電極内不要反射波３は所定の時間
遅れを持つて受信用電極に伝達されるため、素子
の振幅特性及び群遅延特性に悪影響を及ぼすので
ある。 In other words, this unnecessary reflected wave 3 within the electrode is transmitted to the receiving electrode with a predetermined time delay, which adversely affects the amplitude characteristics and group delay characteristics of the element.
本発明に係る弾性表面波装置は、この従来の装
置での難点を解決し、電極内不要反射波を低減
し、周波数特性と時間的特性の良好な装置を提供
するものである。 The surface acoustic wave device according to the present invention solves the problems with the conventional device, reduces unnecessary reflected waves within the electrodes, and provides a device with good frequency characteristics and temporal characteristics.
第２図は、本発明に係る弾性表面波装置の実施
例の電極構造を示す図、又第４図は、本発明に係
る弾性表面波装置の実施例の構造を示す斜視図で
ある。 FIG. 2 is a diagram showing the electrode structure of an embodiment of the surface acoustic wave device according to the present invention, and FIG. 4 is a perspective view showing the structure of the embodiment of the surface acoustic wave device according to the present invention.
第２図及び第４図に示すように、本発明に係る
弾性表面波装置では、電極が互に交差する部分は
従来のようにダブルフインガ構造を有し、電極が
互に交差しない部分はシングル構造を有してい
る。 As shown in FIGS. 2 and 4, in the surface acoustic wave device according to the present invention, the portions where the electrodes intersect each other have a double finger structure as in the prior art, and the portions where the electrodes do not intersect each other have a single finger structure. have.
又、ダブルフインガ構造の電極交差部分を伝播
する表面平面波の波面と、シングル構造の電極非
交差部分を伝播する表面平面波の波面とがずれを
生じないように、シングル構造の電極非交差部分
の電極幅を設定し、隣接する電極の非交差部分が
互に平行とならないように設定してある。 In addition, the electrode width of the non-intersecting portion of the single structure is adjusted so that the wavefront of the surface plane wave propagating through the electrode non-intersecting portion of the double-finger structure does not deviate from the wavefront of the surface plane wave propagating through the non-intersecting portion of the single structure. are set so that non-intersecting portions of adjacent electrodes are not parallel to each other.
このような電極構造にすると、電極の非交差部
分では隣接電極からの反射信号の位相が、表面波
の伝播方向と直角な各点で異なることになり、電
極内不要反射波は相殺されることになる。 With such an electrode structure, the phase of the reflected signal from the adjacent electrode will differ at each point perpendicular to the propagation direction of the surface wave in the non-intersecting portions of the electrodes, and unnecessary reflected waves within the electrodes will be canceled out. become.
第２図及び第４図に示す実施例は、テレビ受信
機の映像中間周波用弾性表面波フイルタとして、
本発明に係る弾性表面波装置を使用したものであ
る。 The embodiment shown in FIGS. 2 and 4 is used as a surface acoustic wave filter for video intermediate frequency of a television receiver.
The surface acoustic wave device according to the present invention is used.
第４図に示すように、128゜ＹカツトＸ伝播の
ニオブ酸リチウム単結晶の圧電性基板４０上に、
重み付電極４１及び正規形電極４２が、フオトリ
ソグラフイの手段で形成された構造となつてい
る。 As shown in FIG. 4, on a piezoelectric substrate 40 of lithium niobate single crystal with 128° Y-cut
The weighted electrode 41 and the regular electrode 42 have a structure formed by means of photolithography.
重み付電極４１及び正規形電極４２は、Ａ１で
作成されその厚みは約１μｍに形成されている。 The weighted electrode 41 and the regular electrode 42 are made of A1 and have a thickness of approximately 1 μm.
重み付電極４１の交差部分は、所定の周波数特
性に基づきフーリエ変換で求められるインパルス
が発生するように、その交差幅及び電極幅を変化
させたダブルフインガ構造となつている。 The intersection of the weighted electrodes 41 has a double finger structure in which the intersection width and the electrode width are changed so that an impulse determined by Fourier transform based on predetermined frequency characteristics is generated.
又、第２図に示すように、非交差部分は従来の
ダミー電極を隣接する主電極に吸収し、重み付電
極全体として波面位相がそろうような電極幅を有
するシングル構造で、表面波の伝播方向に対して
順次１゜ずつ傾斜を変化させ、重み付電極全体と
して−30゜から＋30゜の範囲で傾斜させた形状を
とつている。 In addition, as shown in Figure 2, the non-intersecting part absorbs the conventional dummy electrode into the adjacent main electrode, and has a single structure with an electrode width that aligns the wavefront phase for the entire weighted electrode, which improves the propagation of surface waves. The inclination is sequentially changed by 1° in each direction, and the weighted electrode as a whole has a shape inclined in the range of -30° to +30°.
ここで、正規形電極４２にはダブルフインガ構
造が採用されている。 Here, the regular electrode 42 has a double finger structure.
第３図は本発明に係る弾性表面波装置の実施例
の効果を示す図である。 FIG. 3 is a diagram showing the effects of the embodiment of the surface acoustic wave device according to the present invention.
本発明に係る弾性表面波装置を使用し、バース
ト信号発生器を使用して時間軸上での特性を観測
すると、第３図の主信号３１に対する不要反射信
号３２の強度は、従来では約−30dBから約−
40dBに低減していることが明らかにされた。 When using the surface acoustic wave device according to the present invention and observing the characteristics on the time axis using a burst signal generator, the intensity of the unnecessary reflected signal 32 with respect to the main signal 31 in FIG. 30dB to approx.
It was revealed that the reduction was 40dB.
又、本発明に係る弾性表面波装置は、従来のも
のに比較してダブルフインガ構造部分をほぼ1/3
に縮小することが可能で、素子特性のばらつきに
基づく特性の不均一性を改善し、製品の歩留りを
向上することも出来る。 In addition, the surface acoustic wave device according to the present invention has a double finger structure reduced to approximately 1/3 compared to the conventional surface acoustic wave device.
It is also possible to improve the non-uniformity of characteristics due to variations in device characteristics and improve the yield of products.
以上詳細に説明したように、本発明に係る弾性
表面波装置によれば、弾性表面波フイルタのダミ
ー電極からの電極内不要反射波を低減し、時間軸
上の遅れ信号も除去可能で、構造上もダブルフイ
ンガ部分を縮小し特性の均一化と製品の歩留りを
実現することが出来る。 As explained in detail above, according to the surface acoustic wave device according to the present invention, it is possible to reduce unnecessary reflected waves within the electrode from the dummy electrode of the surface acoustic wave filter, and also to remove delayed signals on the time axis. By reducing the double finger part on the top, it is possible to achieve uniform characteristics and product yield.
第１図は従来使用されているダブルフインガ構
造でダミー電極を有する重み付電極の構造を示す
図、第２図は本発明に係る弾性表面波装置の実施
例の電極構造を示す図、第３図は本発明に係る弾
性表面波装置の実施例の効果を示す図、第４図は
本発明に係る弾性表面波装置の実施例の構造を示
す斜視図である。
符号の説明、１……電極主要部、２……ダミー
電極、３……電極内不要反射波、３１……主信
号、３２……不要反射信号、４０……圧電性基
板、４１……重み付電極、４２……正規形電極。
FIG. 1 is a diagram showing the structure of a conventionally used weighted electrode having a double finger structure and a dummy electrode, FIG. 2 is a diagram showing the electrode structure of an embodiment of the surface acoustic wave device according to the present invention, and FIG. 4 is a diagram showing the effects of the embodiment of the surface acoustic wave device according to the present invention, and FIG. 4 is a perspective view showing the structure of the embodiment of the surface acoustic wave device according to the present invention. Explanation of symbols, 1... Main electrode part, 2... Dummy electrode, 3... Unnecessary reflected wave within the electrode, 31... Main signal, 32... Unnecessary reflected signal, 40... Piezoelectric substrate, 41... Weight Attached electrode, 42...Regular type electrode.
Claims (1)
表面波装置において、ダブルフインガ構造の電極
交差部分を伝播する表面波の波面と電極非交差部
分を伝播する表面波の波面がずれないようにシン
グル構造の前記電極非交差部分の電極幅を設定し
隣接する前記電極非交差部分を互に非平行に配設
することを特徴とする弾性表面波装置。1. In a surface acoustic wave device equipped with comb-shaped electrodes whose crossing width is not constant, the wavefront of the surface wave propagating through the electrode crossing part of the double finger structure and the wave front of the surface wave propagating through the non-crossing part of the electrodes are not shifted. A surface acoustic wave device characterized in that the electrode width of the non-intersecting portions of the electrodes is set, and adjacent non-intersecting portions of the electrodes are arranged non-parallel to each other.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5451378A JPS54146991A (en) | 1978-05-10 | 1978-05-10 | Elastic surface wave device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5451378A JPS54146991A (en) | 1978-05-10 | 1978-05-10 | Elastic surface wave device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS54146991A JPS54146991A (en) | 1979-11-16 |
| JPS6138647B2 true JPS6138647B2 (en) | 1986-08-30 |
Family
ID=12972717
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5451378A Granted JPS54146991A (en) | 1978-05-10 | 1978-05-10 | Elastic surface wave device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS54146991A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5656024A (en) * | 1979-10-11 | 1981-05-16 | Murata Mfg Co Ltd | Elastic surface wave device |
-
1978
- 1978-05-10 JP JP5451378A patent/JPS54146991A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS54146991A (en) | 1979-11-16 |
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