JPH08265091A - Surface acoustic wave device - Google Patents
Surface acoustic wave deviceInfo
- Publication number
- JPH08265091A JPH08265091A JP6459595A JP6459595A JPH08265091A JP H08265091 A JPH08265091 A JP H08265091A JP 6459595 A JP6459595 A JP 6459595A JP 6459595 A JP6459595 A JP 6459595A JP H08265091 A JPH08265091 A JP H08265091A
- Authority
- JP
- Japan
- Prior art keywords
- electrode
- electrode fingers
- floating dummy
- acoustic wave
- surface acoustic
- 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
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、ポケットベル、自動車
電話等移動体通信機器で使用されるＳＡＷフィルタ等の
弾性表面波（ＳＡＷ：Surface Acoustic Wave)デバイス
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave (SAW) device such as a SAW filter used in mobile communication equipment such as pagers and car telephones.
【０００２】[0002]
【従来の技術】ＳＡＷデバイスは圧電基板表面における
弾性表面波の伝搬を利用して電気信号の瀘波、共振等を
実現するデバイスである。ＳＡＷデバイスにおいては、
通常、インタディジタル電極（ＩＤＴ：Inter Digital
Transducer）と呼ばれる電極が使用される。ＩＤＴは、
一対のバスバー及びこのバスバーから指交叉状に延設さ
れた電極指により構成され、ニオブ酸リチウム（ＬｉＮ
ｂＯ3 ）等の圧電基板上に形成される。ＩＤＴに電気信
号を与えると、電気機械変換により電極指間隔に応じた
波長の弾性表面波が発生し圧電基板上を伝搬する。この
弾性表面波を他のＩＤＴにて受波し機械電気変換する
と、専ら電気機械変換、機械電気変換及び送受波間の伝
搬遅延により定まる特性にて瀘波された電気信号が得ら
れる。このような性質を利用したＳＡＷフィルタをはじ
め、各種のＳＡＷデバイスが、各種通信機器において多
く利用されている。2. Description of the Related Art A SAW device is a device that realizes filtering and resonance of an electric signal by utilizing the propagation of surface acoustic waves on the surface of a piezoelectric substrate. For SAW devices,
Usually, an inter digital electrode (IDT: Inter Digital
An electrode called Transducer) is used. IDT is
It is composed of a pair of bus bars and electrode fingers extending from the bus bars in a finger-crossing shape, and is made of lithium niobate (LiN
It is formed on a piezoelectric substrate such as bO 3 ). When an electric signal is applied to the IDT, a surface acoustic wave having a wavelength corresponding to the electrode finger spacing is generated by electromechanical conversion and propagates on the piezoelectric substrate. When this surface acoustic wave is received by another IDT and subjected to mechanical-electrical conversion, an electric signal filtered by a characteristic determined exclusively by electromechanical conversion, mechanical-electrical conversion, and propagation delay between transmission and reception is obtained. Various SAW devices such as SAW filters utilizing such properties are widely used in various communication devices.
【０００３】ＳＡＷデバイスの特性を設計するために
は、送受波双方又はいずれかのＩＤＴに重み付けを施す
必要がある。重み付けの方法としては、電極指の長さに
よる重み付け、電極指の間隔による重み付け、電極指の
太さによる重み付け等、各種の方法が知られている。簡
便な重み付け方法として従来から知られているのは、図
１１に示されるように、＋バスバー１０及び−バスバー
１２から延設される電極指１４を選択的に間引く間引き
重み付けである。重み付け電極は、通常、正規型ＩＤＴ
（重み付けが施されていないＩＤＴ）と共に使用され
る。例えばＳＡＷフィルタの場合、入力ＩＤＴ（送波
側）に重み付けＩＤＴを、出力ＩＤＴ（受波側）ＩＤＴ
に正規型ＩＤＴを、それぞれ使用する。In order to design the characteristics of the SAW device, it is necessary to weight both the transmitting and receiving waves and / or the IDT. As a weighting method, various methods such as weighting by the length of the electrode fingers, weighting by the distance between the electrode fingers, weighting by the thickness of the electrode fingers, etc. are known. As conventionally known as a simple weighting method, as shown in FIG. 11, there is thinning weighting for selectively thinning out the electrode fingers 14 extending from the + bus bar 10 and the − bus bar 12. The weighting electrode is usually a regular IDT
It is used with (unweighted IDT). For example, in the case of a SAW filter, a weighted IDT is applied to the input IDT (transmission side) and an output IDT (reception side) IDT is used.
The normal type IDT is used for each.
【０００４】ＩＤＴにおける電極指構造としては、シン
グル電極構造やダブル電極構造が知られている。シング
ル電極構造は、各バスバーから指交叉状に延設する電極
指が１本ずつの構造である。すなわち、＋バスバーから
１本電極指が延設され、所定間隔を隔てて−バスバーか
ら１本電極指が延設される構造を繰り返して、電極指を
配設する構造である。これに対し、ダブル電極構造は、
各バスバーから指交叉状に延設する電極指が２本ずつの
構造である。すなわち、図８に概念的に示されるよう
に、＋バスバーから２本電極指１４が延設され、所定間
隔を隔てて−バスバーから２本電極指１４が延設される
構造を繰り返して、電極指１４を配設する構造である。
ダブル電極構造は、シングル電極構造に比べ通過帯域内
リプルを低減できるという利点を有しており、従来技術
としてダブル電極構造の間引き重み付けＩＤＴが存在し
た。図９、図１０はダブル電極構造のＩＤＴの間引き部
の例を示す。図１１はダブル電極構造の間引き重み付け
ＩＤＴの具体的な設計例である。図１２は図９に示すＳ
ＡＷデバイスの弾性表面波進行方向に沿った断面の概略
図であり、図中１８はニオブ酸リチウム等から形成され
る圧電基板である。As the electrode finger structure in the IDT, a single electrode structure and a double electrode structure are known. The single electrode structure is a structure in which one electrode finger extends from each bus bar in a finger-crossing shape. That is, the electrode fingers are arranged by repeating the structure in which one electrode finger extends from the + bus bar and one electrode finger extends from the-bus bar at a predetermined interval. On the other hand, the double electrode structure is
The structure has two electrode fingers extending from each bus bar in a finger-crossing shape. That is, as conceptually shown in FIG. 8, the structure in which the two electrode fingers 14 are extended from the + bus bar and the two electrode fingers 14 are extended from the − bus bar at a predetermined interval is repeated to repeat the electrode. This is a structure in which the fingers 14 are arranged.
The double electrode structure has an advantage that ripples in the pass band can be reduced as compared with the single electrode structure, and the thinning weighted IDT of the double electrode structure exists as a conventional technique. 9 and 10 show an example of the thinning section of the IDT having the double electrode structure. FIG. 11 is a specific design example of a thinning-out weighting IDT having a double electrode structure. FIG. 12 shows S shown in FIG.
FIG. 1 is a schematic view of a cross section of an AW device along a surface acoustic wave traveling direction, in which 18 is a piezoelectric substrate formed of lithium niobate or the like.
【０００５】しかし、ダブル電極構造のＩＤＴを間引き
重み付けすると、通過帯域内に振幅特性の落ち込みすな
わち挿入損失が増加する部分が生じるという問題があ
る。これは図１２に示すように電極指１４を間引かない
部分の基板での弾性表面波の伝搬速度ｖ0 と電極指を間
引いた部分の基板での伝搬速度ｖ1 とは相違し、この結
果、弾性表面波とＩＤＴに加える電気信号との位相のず
れが発生するためである。However, when the IDT having the double electrode structure is thinned and weighted, there is a problem in that there is a portion in the pass band where the amplitude characteristic drops, that is, the insertion loss increases. This is different from the propagation velocity v 0 of the surface acoustic wave on the substrate where the electrode fingers 14 are not thinned and the propagation velocity v 1 on the substrate where the electrode fingers are thinned as shown in FIG. This is because a phase shift occurs between the surface acoustic wave and the electric signal applied to the IDT.
【０００６】図１３、図１４には、図１１の従来例の挿
入損失特性が示されている。図１３に示されるのは３ト
ランスデューサ構成の測定結果、図１４に示されるのは
２トランスデューサ構成のシミュレーション結果による
特性である。図中に示される条件のうち“λ0 ／１２Ｆ
ＥＵＤＴ”は、浮き電極単一方向性トランスデューサ
（ＦＥＵＤＴ）、すなわちいずれのバスバーにも接続さ
れていない電極指（浮き電極）を中心波長λ0 の１／１
２だけ本来の電極指位置からずらして設け、方向性を持
たせたＩＤＴを指す。また、２トランスデューサとは、
図１５（ａ）に示されるように入力ＩＤＴ２０及び出力
ＩＤＴ２２がいずれも１個の構成をいい、３トランスデ
ューサとは、図１５（ｂ）に示されるように入力ＩＤＴ
２０が１個で出力ＩＤＴ２２が２個の構成をいう。一般
に、３トランスデューサ構成のほうが、損失が小さい。
図１３、図１４に示されるように従来例では、位相ずれ
による顕著な落ち込みが生じている。FIG. 13 and FIG. 14 show the insertion loss characteristics of the conventional example of FIG. FIG. 13 shows the measurement result of the three-transducer configuration, and FIG. 14 shows the characteristic of the simulation result of the two-transducer configuration. Of the conditions shown in the figure, “λ 0 / 12F
EUDT "is a floating electrode unidirectional transducer (FEUDT), that is, an electrode finger (floating electrode) that is not connected to any bus bar, and has a center wavelength λ 0 of 1/1.
2 indicates an IDT that is provided with a deviation from the original electrode finger position and has a directivity. Also, with 2 transducers,
As shown in FIG. 15A, the input IDT 20 and the output IDT 22 both have a single configuration, and three transducers are the input IDTs as shown in FIG. 15B.
The number 20 is one and the number of output IDTs 22 is two. Generally, the three-transducer configuration has lower loss.
As shown in FIGS. 13 and 14, in the conventional example, a noticeable dip occurs due to the phase shift.
【０００７】またダブル電極構造の間引き重み付けをし
たＩＤＴでは、阻止帯域のスプリアスが生じるという問
題もあった。In addition, the IDT having a double electrode structure with thinning-out has a problem that spurious in the stop band occurs.
【０００８】[0008]
【発明が解決しようとする課題】上述したようにダブル
電極構造のＩＤＴを間引き重み付けすると、通過帯域内
の振幅特性の落ち込みすなわち挿入損失の増加部分や、
阻止帯域のスプリアスという問題が生ずる。本発明はこ
の前者を解決するＳＡＷデバイスと、問題点の双方を解
決した良好な特性を有するＳＡＷデバイスとを提供する
ことを目的とする。When the IDT having the double electrode structure is thinned and weighted as described above, a drop in the amplitude characteristic in the pass band, that is, a portion where the insertion loss increases,
The problem of stopband spurious arises. An object of the present invention is to provide a SAW device that solves the former and a SAW device that has both of the problems and has good characteristics.
【０００９】[0009]
【課題を解決するための手段】このような目的を達成す
るために、本発明のＳＡＷデバイスは、間引き重み付け
されたダブル電極構造ＩＤＴを備えるＳＡＷデバイスに
おいて、弾性表面波の伝搬速度が間引き部と非間引き部
とでほぼ等しくなるよう、ＩＤＴにおける電極指の間引
き部に、浮きダミー電極を設けることを特徴とする。In order to achieve such an object, the SAW device of the present invention is a SAW device including a thin electrode IDT having a double electrode structure, in which the propagation velocity of surface acoustic waves is different from that of the thinning portion. A floating dummy electrode is provided in the thinned-out portion of the electrode fingers in the IDT so that the non-thinned-out portion is almost equal.
【００１０】[0010]
【作用】通過帯域内での振幅特性の落ち込みは、間引き
部の占有面積が割合として大きく、間引き部での弾性表
面波の伝搬速度と非間引き部での伝搬速度との差により
位相ずれが生ずることにより発生していた。本発明のＳ
ＡＷデバイスにおいては、ＩＤＴにおける電極指の間引
き部にいずれのバスバーにも接続されず電気的に浮いて
いる浮きダミー電極が配置形成される。The drop of the amplitude characteristic in the pass band is occupying a large area in the thinning portion, and a phase shift occurs due to the difference between the propagation velocity of the surface acoustic wave in the thinning portion and the propagation velocity in the non-thinning portion. It was caused by this. S of the present invention
In the AW device, a floating dummy electrode which is electrically connected and is not connected to any bus bar is arranged and formed in the thinned portion of the electrode finger in the IDT.
【００１１】この浮きダミー電極により弾性表面波の伝
搬についての機械的条件は電極指が存在しているのと同
様になる。この結果、弾性表面波の伝搬速度が間引き部
と非間引き部とでほぼ等しくなり、位相ずれが低減乃至
防止される結果、通過帯域内での振幅特性の落ち込みが
無くなる。さらに請求項３に対応する本発明による浮き
ダミー電極を設けた部では、ＩＤＴの電極指による電界
が緩やかになり阻止帯域のスプリアスが抑制される。With this floating dummy electrode, the mechanical conditions for the propagation of the surface acoustic wave are the same as the presence of electrode fingers. As a result, the propagation velocity of the surface acoustic wave becomes substantially equal in the thinned portion and the non-thinned portion, and the phase shift is reduced or prevented. As a result, the amplitude characteristic does not drop in the pass band. Further, in the portion provided with the floating dummy electrode according to the present invention corresponding to claim 3, the electric field due to the electrode fingers of the IDT becomes gentle, and spurious in the stop band is suppressed.
【００１２】[0012]
【実施例】以下、本発明の好適な実施例について図面に
基づき説明する。なお、各図において同様の構成要素に
は同一の符号を付し説明を省略する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. In addition, in each figure, the same components are denoted by the same reference numerals, and the description thereof will be omitted.
【００１３】図１は請求項１に対応する本発明の実施例
であり、図９のニオブ酸リチウム等の圧電基板上に形成
されたＩＤＴの電極指の間引き部に浮きダミー電極２６
が挿入されている。浮きダミー電極２６はバスバーに接
続されておらず、複数の指状電極がその一端で互いに電
気的に接続された形状を有している。すなわち本実施例
では、同一のバスバーに接続されている２本の電極指が
挟む所定の間引き部に、１つの浮きダミー電極が配置さ
れ、この浮きダミー電極はいずれのバスバーにも接続さ
れないので、電界を発生しない。FIG. 1 shows an embodiment of the present invention corresponding to claim 1, which is a dummy electrode 26 floating on the thinned portion of the electrode finger of the IDT formed on the piezoelectric substrate such as lithium niobate of FIG.
Has been inserted. The floating dummy electrode 26 is not connected to the bus bar and has a shape in which a plurality of finger electrodes are electrically connected to each other at one end thereof. That is, in this embodiment, one floating dummy electrode is arranged in a predetermined thinning portion sandwiched by two electrode fingers connected to the same bus bar, and this floating dummy electrode is not connected to any bus bar. Does not generate an electric field.
【００１４】図５は図１に示すＳＡＷデバイスの弾性表
面波進行方向に沿った断面の概略図であり、電極指１４
を間引かない部分の基板と浮きダミー電極２６を設けた
部分の基板との機械的条件は同様になる。その結果、電
極指１４を間引かない部分の基板での弾性表面波の伝搬
速度ｖ0 と浮きダミー電極を設けた部分の基板での伝搬
速度ｖ2 とがほぼ等しくなり、位相ずれが低減ないし防
止される結果、通過帯域内での振幅特性の落ち込みが無
くなる。FIG. 5 is a schematic view of a section of the SAW device shown in FIG. 1 along the surface acoustic wave traveling direction.
The mechanical conditions of the part of the substrate where thin film is not thinned are the same as those of the part where the floating dummy electrode 26 is provided. As a result, the propagation velocity v 0 of the surface acoustic wave on the substrate where the electrode fingers 14 are not thinned and the propagation velocity v 2 on the substrate where the floating dummy electrode is provided are substantially equal, and the phase shift is not reduced. As a result, the drop of the amplitude characteristic within the pass band is eliminated.
【００１５】図２は請求項２に対応する本発明の第二の
実施例であり、図１０のＩＤＴの電極指の間引き部に浮
きダミー電極３６が挿入されている。浮きダミー電極３
６はバスバーに接続されておらず、複数の指状電極がそ
の一端で互いに電気的に接続された形状を有している。
すなわち本実施例では、異なるバスバーに接続されてい
る２本の電極指が挟む所定の間引き部に、１つの浮きダ
ミー電極が配置され、この浮きダミー電極はいずれのバ
スバーにも接続されない。このＳＡＷデバイスにおいて
も弾性表面波進行方向の断面図は図５となり、この本実
施例の効果として、上記本発明の第一の実施例と同様の
通過帯域内での振幅特性の改善の効果が得られる。FIG. 2 shows a second embodiment of the present invention corresponding to claim 2, and a floating dummy electrode 36 is inserted in the thinned portion of the electrode finger of the IDT of FIG. Floating dummy electrode 3
Reference numeral 6 is not connected to the bus bar, and has a shape in which a plurality of finger electrodes are electrically connected to each other at one end thereof.
That is, in this embodiment, one floating dummy electrode is arranged in a predetermined thinning portion sandwiched by two electrode fingers connected to different bus bars, and this floating dummy electrode is not connected to any bus bar. Also in this SAW device, a sectional view in the traveling direction of the surface acoustic wave is shown in FIG. 5, and as the effect of this embodiment, the effect of improving the amplitude characteristic in the pass band similar to that of the first embodiment of the present invention is obtained. can get.
【００１６】図３は請求項３に対応する本発明の第三の
実施例である。本発明が実施される電極指の間引き部
は、図１０の場合と同じく、互いに異なるバスバーに接
続されている２本の電極指１４に挟まれており、この間
引き部に４本の電極指の一端を接続した浮きダミー電極
４６が７個配置されている。図２に示した実施例との本
質的な差異は、浮きダミー電極４６が電気的に互いに分
離された複数の浮きダミー電極である点である。本実施
例においても上記本発明の第一及び第二の実施例で述べ
た効果を得られる。本実施例では第二の効果として、バ
スバー１０、１２から間引き部を挟む２つのダブル電極
指１４にそれぞれ正負の電気信号が加えられたとき、浮
きダミー電極４６の個々の静電誘導により、間引き部で
の電界のかかり方が第二の実施例より滑らかになるた
め、阻止帯域のスプリアスが減少するという効果が得ら
れる。FIG. 3 shows a third embodiment of the present invention corresponding to claim 3. Similar to the case of FIG. 10, the thinned-out portion of the electrode fingers in which the present invention is implemented is sandwiched between two electrode fingers 14 connected to different bus bars, and the thinned-out portion includes four electrode fingers. Seven floating dummy electrodes 46 connected to one end are arranged. The essential difference from the embodiment shown in FIG. 2 is that the floating dummy electrodes 46 are a plurality of floating dummy electrodes that are electrically separated from each other. Also in this embodiment, the effects described in the first and second embodiments of the present invention can be obtained. In the present embodiment, as a second effect, when positive and negative electric signals are applied to the two double electrode fingers 14 sandwiching the thinning portion from the bus bars 10 and 12, thinning is performed by individual electrostatic induction of the floating dummy electrode 46. Since the electric field applied to the part is smoother than that in the second embodiment, the effect of reducing spurious in the stop band can be obtained.
【００１７】図４は請求項１に対応する本発明と、請求
項２に対応する本発明を使用した具体的な設計例であ
る。本実施例は図１１の間引き重み付けＩＤＴに浮きダ
ミー電極３６及びバスバーに接続されたダミー電極を使
用したものである。FIG. 4 shows a concrete design example using the present invention corresponding to claim 1 and the present invention corresponding to claim 2. In this embodiment, the floating dummy electrode 36 and the dummy electrode connected to the bus bar are used in the thinning weighting IDT shown in FIG.
【００１８】図６、図７には、本実施例の挿入損失特性
が示されている。図６に示されるのは３トランスデュー
サ構成の実施例の測定結果、図７に示されるのは２トラ
ンスデューサ構成の実施例のシミュレーション結果によ
る特性である。これらの特性は、トランスデューサ配置
や中心周波数が異なる他は、図１３、図１４に示される
従来例と同一条件にて得られた特性である。6 and 7 show the insertion loss characteristics of this embodiment. FIG. 6 shows the measurement result of the example of the three-transducer configuration, and FIG. 7 shows the characteristic of the simulation result of the example of the two-transducer configuration. These characteristics are characteristics obtained under the same conditions as the conventional example shown in FIGS. 13 and 14 except that the transducer arrangement and the center frequency are different.
【００１９】図１３に示される３トランスデューサの従
来例では、位相ずれによる顕著な特性の落ち込みが生じ
ていたのに対し、図６に示される３トランスデューサの
本発明の実施例では、帯域内において特性の落ち込みは
生じておらずかつ帯域内リプルもピークトゥピークで約
１．４ｄＢにとどまっている。図１４に示される２トラ
ンスデューサの従来例でも顕著な特性の落ち込みが生じ
ていたが、図７に示される２トランスデューサの本発明
の実施例では帯域内の特性の落ち込みは生じていない。In the conventional example of the three transducers shown in FIG. 13, a remarkable drop in the characteristics is caused by the phase shift, whereas in the embodiment of the present invention of the three transducers shown in FIG. 6, the characteristics are within the band. Has not occurred, and the ripple in the band is about 1.4 dB peak-to-peak. In the conventional example of the two-transducer shown in FIG. 14, the characteristic drop is remarkable, but in the embodiment of the present invention of the two-transducer shown in FIG. 7, the characteristic drop in the band is not occurred.
【００２０】[0020]
【発明の効果】以上説明したように、本発明のＳＡＷデ
バイスによれば、ＩＤＴにおける電極指の間引き部に浮
きダミー電極を配置形成するようにしたため、弾性表面
波の伝搬速度が間引き部と非間引き部とでほぼ等しくな
り、位相ずれが低減乃至防止される結果、通過帯域内で
の振幅特性の落ち込みが無くなる。As described above, according to the SAW device of the present invention, since the floating dummy electrode is arranged and formed in the thinned portion of the electrode finger in the IDT, the propagation velocity of the surface acoustic wave is different from that of the thinned portion. As a result, it becomes almost equal in the thinning section and the phase shift is reduced or prevented. As a result, there is no drop in the amplitude characteristic within the pass band.
【００２１】また請求項３に対応する本発明では、浮き
ダミー電極は静電誘導により電界を発生し、間引き部で
のＩＤＴの電界のかかり方が滑らかになり、インパルス
応答の乱れが防止されるため、阻止帯域のスプリアスが
減少する。Further, in the present invention corresponding to claim 3, the floating dummy electrode generates an electric field by electrostatic induction, the IDT electric field is applied smoothly in the thinning portion, and the impulse response is prevented from being disturbed. Therefore, the spurious in the stop band is reduced.
【図１】 本発明の第一の実施例における電極構造を概
念的に示す平面図である。FIG. 1 is a plan view conceptually showing an electrode structure in a first embodiment of the present invention.
【図２】 本発明の第二の実施例における電極構造を概
念的に示す平面図である。FIG. 2 is a plan view conceptually showing an electrode structure in a second embodiment of the present invention.
【図３】 本発明の第三の実施例における電極構造を概
念的に示す平面図である。FIG. 3 is a plan view conceptually showing an electrode structure in a third embodiment of the present invention.
【図４】 本発明の実施例の電極配置の具体例を示す平
面図である。FIG. 4 is a plan view showing a specific example of the electrode arrangement according to the embodiment of the present invention.
【図５】 本発明における浮きダミー電極の効果を示す
ＳＡＷデバイス断面図である。FIG. 5 is a SAW device sectional view showing the effect of the floating dummy electrode in the present invention.
【図６】 実施例における挿入損失特性を示す図であ
る。FIG. 6 is a diagram showing insertion loss characteristics in the example.
【図７】 実施例における挿入損失特性を示す図であ
る。FIG. 7 is a diagram showing insertion loss characteristics in the example.
【図８】 ダブル電極構造を概念的に示す平面図であ
る。FIG. 8 is a plan view conceptually showing a double electrode structure.
【図９】 電極の間引き例を示す平面図である。FIG. 9 is a plan view showing an example of thinning electrodes.
【図１０】 電極の間引き例を示す平面図である。FIG. 10 is a plan view showing an example of thinning electrodes.
【図１１】 従来の電極配置の具体例を示す平面図であ
る。FIG. 11 is a plan view showing a specific example of a conventional electrode arrangement.
【図１２】 従来の電極の効果を示すＳＡＷデバイス断
面図である。FIG. 12 is a sectional view of a SAW device showing the effect of a conventional electrode.
【図１３】 従来における挿入損失特性を示す図であ
る。FIG. 13 is a diagram showing a conventional insertion loss characteristic.
【図１４】 従来における挿入損失特性を示す図であ
る。FIG. 14 is a diagram showing a conventional insertion loss characteristic.
【図１５】 トランスデューサの配置を説明する平面図
である。FIG. 15 is a plan view illustrating the arrangement of transducers.
１０ ＋バスバー、１２ −バスバー、１４ 電極指、
１８ 圧電基板、２０入力ＩＤＴ、２２ 出力ＩＤＴ、
２６，３６，４６ 浮きダミー電極。10 + busbar, 12-busbar, 14 electrode fingers,
18 piezoelectric substrate, 20 input IDT, 22 output IDT,
26, 36, 46 Floating dummy electrodes.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 笹原 謙一 神奈川県横浜市港北区菊名７−３−16 大 井電気株式会社内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichi Sasahara 7-3-16 Kikuna, Kohoku Ward, Yokohama City, Kanagawa Oi Electric Co., Ltd.
Claims (3)
する圧電基板と、圧電基板の表面に形成された２本のバ
スバー及びこのバスバーから指交叉状に延設された複数
の電極指を有し電極指の間引きにより重み付けされたイ
ンタディジタル電極とを備え、インタディジタル電極の
電極指が一方のバスバーからの２本の指状電極を対で設
けたダブル電極構造を有するＳＡＷデバイスにおいて、 弾性表面波の伝搬速度が間引き部と非間引き部とでほぼ
等しくなるよう、同一のバスバーに接続されているイン
タディジタル電極の電極指に挟まれた所定の間引き部に
いずれのバスバーにも接続されていない浮きダミー電極
を設けたことを特徴とするＳＡＷデバイス。1. A piezoelectric substrate having a surface acoustic wave generated on its surface by excitation, two bus bars formed on the surface of the piezoelectric substrate, and a plurality of electrode fingers extending from the bus bar in a finger-crossing shape. A SAW device having an interdigital electrode weighted by thinning out the electrode fingers, the electrode fingers of the interdigital electrode having a double electrode structure in which two finger-shaped electrodes from one busbar are provided in pairs. Neither busbar is connected to the predetermined thinning part sandwiched between the electrode fingers of the interdigital electrodes connected to the same busbar so that the wave propagation speeds are almost equal in the thinning part and the non-thinning part A SAW device having a floating dummy electrode.
する圧電基板と、圧電基板の表面に形成された２本のバ
スバー及びこのバスバーから指交叉状に延設された複数
の電極指を有し電極指の間引きにより重み付けされたイ
ンタディジタル電極とを備え、インタディジタル電極の
電極指が２本の指状電極を対で設けたダブル電極構造を
有するＳＡＷデバイスにおいて、 弾性表面波の伝搬速度が間引き部と非間引き部とでほぼ
等しくなるよう、異なるバスバーに接続されているイン
タディジタル電極の電極指に挟まれた所定の間引き部に
いずれのバスバーにも接続されていない浮きダミー電極
を設けたことを特徴とするＳＡＷデバイス。2. A piezoelectric substrate which generates a surface acoustic wave on its surface by excitation, two bus bars formed on the surface of the piezoelectric substrate, and a plurality of electrode fingers extending from the bus bar in a finger-crossing shape. In the SAW device having an interdigital electrode weighted by thinning out the electrode fingers, and the electrode fingers of the interdigital electrode having a double electrode structure in which two finger electrodes are provided in pairs, the propagation velocity of the surface acoustic wave is A floating dummy electrode that is not connected to any bus bar is provided in the predetermined thinning part sandwiched between the electrode fingers of the interdigital electrodes connected to different bus bars so that the thinned part and the non-thinned part are almost equal. A SAW device characterized in that
する圧電基板と、圧電基板の表面に形成された２本のバ
スバー及びこのバスバーから指交叉状に延設された複数
の電極指を有し電極指の間引きにより重み付けされたイ
ンタディジタル電極とを備え、インタディジタル電極の
電極指が２本の指状電極を対で設けたダブル電極構造を
有するＳＡＷデバイスにおいて、 弾性表面波の伝搬速度が間引き部と非間引き部とでほぼ
等しくなるよう、異なるバスバーに接続されているイン
タディジタル電極の電極指に挟まれた所定の間引き部に
いずれのバスバーにも接続されていない２以上の浮きダ
ミー電極を設けたことを特徴とするＳＡＷデバイス。3. A piezoelectric substrate, which generates a surface acoustic wave on its surface by excitation, two bus bars formed on the surface of the piezoelectric substrate, and a plurality of electrode fingers extending from the bus bar in a finger-crossing shape. In the SAW device having an interdigital electrode weighted by thinning out the electrode fingers, and the electrode fingers of the interdigital electrode having a double electrode structure in which two finger electrodes are provided in pairs, the propagation velocity of the surface acoustic wave is Two or more floating dummy electrodes that are not connected to any bus bar at a predetermined thinning portion sandwiched between electrode fingers of interdigital electrodes connected to different bus bars so that the thinned portion and the non-thinned portion are almost equal A SAW device characterized by being provided with.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06459595A JP3432323B2 (en) | 1995-03-23 | 1995-03-23 | SAW device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP06459595A JP3432323B2 (en) | 1995-03-23 | 1995-03-23 | SAW device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08265091A true JPH08265091A (en) | 1996-10-11 |
| JP3432323B2 JP3432323B2 (en) | 2003-08-04 |
Family
ID=13262772
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP06459595A Expired - Lifetime JP3432323B2 (en) | 1995-03-23 | 1995-03-23 | SAW device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3432323B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002353777A (en) * | 2001-05-29 | 2002-12-06 | Toyo Commun Equip Co Ltd | Surface acoustic wave filter |
| US6720842B2 (en) | 2000-02-14 | 2004-04-13 | Murata Manufacturing Co., Ltd. | Surface acoustic wave filter device having first through third surface acoustic wave filter elements |
| JP2006108901A (en) * | 2004-10-01 | 2006-04-20 | Epson Toyocom Corp | Unidirectional surface acoustic wave transducer and surface acoustic wave device using the same |
| US11469736B2 (en) | 2017-05-26 | 2022-10-11 | Murata Manufacturing Co., Ltd. | Acoustic wave device, filter, multiplexer, radio-frequency front-end circuit, and communication device |
-
1995
- 1995-03-23 JP JP06459595A patent/JP3432323B2/en not_active Expired - Lifetime
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6720842B2 (en) | 2000-02-14 | 2004-04-13 | Murata Manufacturing Co., Ltd. | Surface acoustic wave filter device having first through third surface acoustic wave filter elements |
| US6744333B2 (en) | 2000-02-14 | 2004-06-01 | Murata Manufacturing Co., Ltd. | Surface acoustic wave filter device with balanced and unbalanced terminals |
| KR100573899B1 (en) * | 2000-02-14 | 2006-04-26 | 가부시키가이샤 무라타 세이사쿠쇼 | Surface acoustic wave filter device |
| JP2002353777A (en) * | 2001-05-29 | 2002-12-06 | Toyo Commun Equip Co Ltd | Surface acoustic wave filter |
| JP2006108901A (en) * | 2004-10-01 | 2006-04-20 | Epson Toyocom Corp | Unidirectional surface acoustic wave transducer and surface acoustic wave device using the same |
| US11469736B2 (en) | 2017-05-26 | 2022-10-11 | Murata Manufacturing Co., Ltd. | Acoustic wave device, filter, multiplexer, radio-frequency front-end circuit, and communication device |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3432323B2 (en) | 2003-08-04 |
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