JP2714189B2 - Surface acoustic wave filter and communication device using the same - Google Patents
Surface acoustic wave filter and communication device using the sameInfo
- Publication number
- JP2714189B2 JP2714189B2 JP1302103A JP30210389A JP2714189B2 JP 2714189 B2 JP2714189 B2 JP 2714189B2 JP 1302103 A JP1302103 A JP 1302103A JP 30210389 A JP30210389 A JP 30210389A JP 2714189 B2 JP2714189 B2 JP 2714189B2
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- width
- electrode
- electrode finger
- surface acoustic
- acoustic wave
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、電極指交叉幅に重み付けしたすだれ状電極
の全ての対向電極指対の電極指交叉幅を、基板上を伝搬
する弾性表面波の中心波長より長くして、回折波の発生
を抑制した弾性表面波フィルタに関する。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a surface acoustic wave propagating on a substrate, in which the electrode finger crossing width of all the counter electrode finger pairs of the IDT weighted to the electrode finger crossing width is determined. The present invention relates to a surface acoustic wave filter that is longer than the center wavelength of the surface acoustic wave and suppresses generation of diffracted waves.
重み付けしたすだれ状電極の電極指交叉幅の短い個所
で回折波が生ずるのを避けるために、従来は、例えば特
開昭50−24050号公報に開示されている、対向電極をそ
の長さ方向に２個または３個以上に分割して得られる浮
遊中間電極を直列接続して成る対向電極部を複数対並列
接続して構成する技術が用いられていた。上記技術は、
対向電極の長さ方向について電極強度の分布がほぼ一様
になるという利点を有している。Conventionally, in order to avoid the occurrence of diffracted waves at locations where the electrode finger crossing width of the weighted interdigital electrodes is short, the counter electrode, for example, disclosed in Japanese Patent Application Laid-Open No. A technique has been used in which a plurality of counter electrode portions formed by serially connecting floating intermediate electrodes obtained by dividing into two or three or more pieces are connected in parallel. The above technology is
There is an advantage that the distribution of the electrode strength becomes substantially uniform in the length direction of the counter electrode.
しかし、上記従来の技術は、分割数が多くなると、や
はり交叉幅が小さくなり回折効果の影響を受けるという
問題があった。However, the above-described conventional technique has a problem that as the number of divisions increases, the intersection width also becomes smaller and is affected by the diffraction effect.
本発明は、上記のような従来の技術の問題を解決し、
電極指交叉幅の小さい個所で生ずる回折効果の影響を抑
圧した弾性表面波フィルタを提供することを目的とす
る。The present invention solves the problems of the prior art as described above,
It is an object of the present invention to provide a surface acoustic wave filter that suppresses the effect of a diffraction effect generated at a place where the electrode finger crossing width is small.
上記目的を達成するために本発明においては、電極指
交叉幅に重み付けをした電極の表面波伝搬方向のある位
置で所望の弾性表面波励振強度を１対の対向電極指で励
振しようとすると基板上を伝搬する表面波の中心波長よ
りも電極指交叉幅が短い狭交叉幅となる場合に、その位
置の電極を表面波伝搬方向に直角な方向で２分割し、各
部分夫々の電極指交叉幅は表面波の中心波長よりも長
く、夫々逆位相の電圧で励振され、夫々の電極指交叉幅
の差が上記狭交叉幅に等しくなるように形成して、基板
上を伝搬する弾性表面波の中心波長よりも長い電極指交
叉幅を有する対向電極対指だけによって、全ての所望の
弾性表面波励振強度を得るようにした。In order to achieve the above object, in the present invention, when a desired surface acoustic wave excitation intensity is to be excited by a pair of counter electrode fingers at a position in the surface wave propagation direction of the electrode weighted to the electrode finger crossing width, When the electrode finger crossing width is shorter than the center wavelength of the surface wave propagating above, the electrode at that position is divided into two in a direction perpendicular to the surface wave propagation direction, and the electrode finger crossing of each part is performed. The width is longer than the center wavelength of the surface acoustic wave, is excited by voltages of opposite phases, and is formed so that the difference between the electrode finger intersection widths is equal to the narrow intersection width, and the surface acoustic wave propagating on the substrate All desired surface acoustic wave excitation intensities are obtained only by the counter electrode pair finger having the electrode finger crossing width longer than the center wavelength of.
上記のようにすれば、２分割された各部分それぞれ励
振された電極指に直角な方向の弾性表面波の強度の和
は、弾性表面波中心波長より短い分割してない１対の対
向電極指交叉部で励振された電極指に直角な方向の弾性
表面波の強度に等しくなり、しかも分割各部夫々の電極
指交叉幅は一般に分割しなかった場合よりも大幅に長く
なっているから、回折効果の影響を非常に良く抑制する
ことが出来る。According to the above, the sum of the strengths of the surface acoustic waves in the direction perpendicular to the electrode fingers excited in each of the two divided portions is a pair of undivided opposed electrode fingers shorter than the center wavelength of the surface acoustic wave. The intensity of the surface acoustic wave in the direction perpendicular to the electrode finger excited at the intersection is equal to the intensity of the surface acoustic wave, and the electrode finger intersection width of each of the divided parts is generally much longer than when not divided, so the diffraction effect Can be suppressed very well.
第１図は本発明第１実施例の模式的平面図である。圧
電性基板１として128度回転Ｙ軸切断Ｘ軸伝搬のニオブ
酸リチウム単結晶を用い、この基板１上に、入力すだれ
状電極２と出力すだれ状電極３が配設され、出力すだれ
状電極３は、従来のすだれ状電極では前記狭交叉幅にな
ってしまう部分Ａの２分割されたすだれ状電極4,5と、
それ以外の部分Ｂのすだれ状電極６から形成されてい
る。入出力電極2,3の両側、即ち基板１の両端部には、
基板端面からの不要反射波を抑圧するため吸音材７が塗
布してある。端子8,8′は入力端子で、端子9,9′は出力
端子である。すだれ状電極4,5を形成する電極中央部バ
スバー10,11は、それぞれ出力端子９′,9に接続されて
いる。また、このフィルタの中心周波数は36.15MHzで、
出力すだれ状電極３の対数は57.5対で最大開口長は1300
μｍ、入力すだれ状電極２の対数は8.5対で最大開口長
は2000μｍである。すだれ状電極４（バスバー10）及び
すだれ状電極５（バスバー11）の弾性表面波伝搬方向ｘ
の任意の位置ｘ′における夫々の電極指交叉幅w1及びw2
は共に基板１を伝搬する弾性表面波の中心波長wsよりも
長く、下部すだれ状電極５は所望の弾性表面波と同相の
励振強度を与え、上部すだれ電極４は逆相の励振強度を
与える。下部すだれ状電極５の交叉幅w2と上部すだれ状
電極４の交叉幅w1の長さの差は、従来の分割しない場合
の交叉幅に等しい。上下に分割したすだれ状電極4,5で
励振される弾性表面波の位相は逆相であって、所望の弾
性表面波励振強度を、それぞれ基板を伝搬する弾性表面
波の中心波長よりも長い開口長で実現できるため、回折
効果を抑圧することが出来る。FIG. 1 is a schematic plan view of the first embodiment of the present invention. A piezoelectric substrate 1 is made of a single crystal of lithium niobate that transmits a 128-degree rotated Y-axis and cuts an X-axis. On this substrate 1, an input interdigital electrode 2 and an output interdigital electrode 3 are arranged. Are divided into two interdigital transducers 4 and 5 of a portion A which becomes the narrow intersection width in the conventional interdigital transducer;
The other portion B is formed from the interdigital electrodes 6. On both sides of the input / output electrodes 2 and 3, that is, on both ends of the substrate 1,
A sound absorbing material 7 is applied to suppress unnecessary reflected waves from the end face of the substrate. Terminals 8, 8 'are input terminals, and terminals 9, 9' are output terminals. The central electrode bus bars 10, 11 forming the interdigital electrodes 4, 5 are connected to output terminals 9 ', 9, respectively. The center frequency of this filter is 36.15MHz,
The number of pairs of output interdigital electrodes 3 is 57.5 pairs and the maximum aperture length is 1300.
μm, the number of pairs of input interdigital electrodes 2 is 8.5, and the maximum aperture length is 2000 μm. Surface acoustic wave propagation direction x of interdigital transducer 4 (bus bar 10) and interdigital transducer 5 (bus bar 11)
Electrode finger cross widths w 1 and w 2 at any position x ′
Are longer than the center wavelength w s of the surface acoustic wave propagating in the substrate 1, the lower interdigital electrode 5 provides an excitation intensity in phase with the desired surface acoustic wave, and the upper interdigital electrode 4 provides an excitation intensity in opposite phase. . The difference in length of the cross width w 1 of the cross width w 2 and the upper interdigital electrode 4 of the lower interdigital electrode 5 is equal to cross width in the case of not conventional split. The surface acoustic waves excited by the vertically interdigitated interdigital electrodes 4 and 5 have opposite phases, and the desired surface acoustic wave excitation intensity is set to be longer than the center wavelength of the surface acoustic wave propagating through the substrate. Since it can be realized with a long length, the diffraction effect can be suppressed.
第２図は同じ弾性表面波励振強度が得られる従来例を
示す。第１図と同様の個所には同じ符号を付す。図中に
示す狭交叉部Ａは不要回折波の原因となる。FIG. 2 shows a conventional example in which the same surface acoustic wave excitation intensity can be obtained. The same parts as those in FIG. 1 are denoted by the same reference numerals. The narrow intersection A shown in the figure causes unnecessary diffraction waves.
第３図は本発明第２実施例の平面図を示す。Ａ部の中
央のバスバー10′,11′は共に出力端子９′に接続さ
れ、これらのバスに接続された電極指は夫々出力端子９
に接続されたすだれ状電極４′,5′の電極指と交叉して
いる。すだれ状電極４′,5′の各電極指間の電界は、弾
性表面波伝搬方向ｘの同位置において逆相になるので、
第１実施例の場合と同様な効果が得られる。更に中央の
バスバー10′,11′が同電位であるため、これらの間で
不要な弾性表面波が励振されるのを避けることができ
る。FIG. 3 shows a plan view of the second embodiment of the present invention. The bus bars 10 'and 11' at the center of the portion A are both connected to the output terminal 9 ', and the electrode fingers connected to these buses are connected to the output terminal 9', respectively.
And intersects with the electrode fingers of the interdigital electrodes 4 'and 5' connected to. Since the electric field between the electrode fingers of the interdigital electrodes 4 'and 5' becomes opposite in phase at the same position in the surface acoustic wave propagation direction x,
The same effect as in the first embodiment can be obtained. Further, since the central bus bars 10 'and 11' have the same potential, unnecessary surface acoustic waves can be prevented from being excited between them.
第４図は本発明第３実施例の平面図を示す。本実施例
は第２実施例の中央のバスバー10′,11′を一つのバス
バー12にしたものである。このようにすれば、第２実施
例と同様な効果が得られ、更に配線数も減少し、製作工
程が改善される。またＡ部を成すすだれ状電極の交叉幅
を選択する自由度も増す。FIG. 4 is a plan view of a third embodiment of the present invention. In this embodiment, the central busbars 10 ', 11' of the second embodiment are replaced by a single busbar 12. By doing so, the same effects as in the second embodiment can be obtained, the number of wirings can be reduced, and the manufacturing process can be improved. Further, the degree of freedom in selecting the cross width of the interdigital transducers forming the portion A is increased.
第５図は本発明第４実施例の出力電極の模式的平面図
である。Ｂ部において出力端子９に接続されたすだれ状
電極14,15は中央の出力端子９′に接続されたすだれ状
電極13とそれぞれ対向電極を成す。すだれ状電極13,14
およびすだれ状電極13,15の各電極指間の電界は、弾性
表面波伝搬方向ｘの同位置において同相となり、それぞ
れの対向電極対の交叉部で励振される弾性表面波は同相
となる。このため、それぞれの対向電極の交叉幅を基板
１を伝わる弾性表面波の中心波長よりも大きく適当に選
ぶことにより第３実施例の場合と同様な効果が得られ
る。更に中央バスバーが出力電極の全体にわたって共通
となるため配線工程が第３実施例よりも簡略化される。FIG. 5 is a schematic plan view of an output electrode according to a fourth embodiment of the present invention. In section B, the interdigital electrodes 14 and 15 connected to the output terminal 9 form counter electrodes with the interdigital electrode 13 connected to the central output terminal 9 '. IDT 13,14
The electric field between the electrode fingers of the interdigital electrodes 13 and 15 has the same phase at the same position in the surface acoustic wave propagation direction x, and the surface acoustic waves excited at the intersections of the respective opposed electrode pairs have the same phase. For this reason, the same effect as in the third embodiment can be obtained by appropriately selecting the cross width of each counter electrode to be larger than the center wavelength of the surface acoustic wave transmitted through the substrate 1. Further, since the central bus bar is common to the entire output electrode, the wiring process is simplified as compared with the third embodiment.
第６図は本発明第５実施例の出力電極の平面図を示
し、第４実施例の場合のすだれ状電極13及び14,15をス
プリットコネクト型のすだれ状電極13′，及び14′,1
5′にしたものである。これにより第４実施例と同様な
効果が得られ、更電極指がスプリットコネクト型である
ため、各対向電極の交叉幅を独立に選択できるため設計
の自由度が増す。FIG. 6 is a plan view of an output electrode according to a fifth embodiment of the present invention. In the case of the fourth embodiment, the interdigital electrodes 13 and 14, 15 are replaced with split-connect type interdigital electrodes 13 ', 14', and 1 '.
5 '. As a result, the same effect as that of the fourth embodiment can be obtained, and since the additional electrode finger is of a split connect type, the crossing width of each counter electrode can be selected independently, so that the degree of freedom of design increases.
第７図は本発明第６実施例の出力電極を示す。出力端
子９に接続されたすだれ状電極16及び出力端子９′に接
続されたすだれ状電極17から伸びる電極指は、電極指18
及び19で代表されるように、表面波伝搬方向に直角な方
向の中間で表面波伝搬方向に表面波中心波長の半波長分
だけ屈曲している。電極指18及び19は、それぞれ弾性表
面波伝搬方向軸ｘの位置x1,x2,x3及び位置x2,x3,x4にお
いて交叉部を成している。位置x3においてすだれ状電極
16から伸びる電極指18とすだれ状電極17から伸びる電極
指19のなす交叉部による電界と、すだれ状電極16から伸
びる電極指20とすだれ状電極17から伸びる電極指19の成
す交叉部による電界は、互いに逆相となっており、それ
ぞれの交叉部で励振される弾性表面波の位相は逆相とな
るため、電極指19及び20の曲がる位置を適当に決め、位
置x3における２個所の交叉部を基板を伝搬する弾性表面
波の中心波長より大きく選ぶことにより回折を抑圧でき
る交叉幅を実現することができ、第１実施例と同様な効
果が得られる。更に弾性表面波伝搬方向に直角な方向に
おける電力分布も連続となり、更に良い周波数特性が得
られる。また、配線引き回し工程も簡易であり、直達波
の影響を抑えると共に製造工程も簡略化される。FIG. 7 shows an output electrode according to a sixth embodiment of the present invention. The electrode fingers extending from the interdigital electrode 16 connected to the output terminal 9 and the interdigital electrode 17 connected to the output terminal 9 ′ are electrode fingers 18.
And 19, it is bent by half the center wavelength of the surface wave in the surface wave propagation direction in the middle of the direction perpendicular to the surface wave propagation direction. The electrode fingers 18 and 19 is formed in a cross section at position x 1, x 2, x 3 and position x 2, x 3, x 4 respectively SAW propagation axis x. IDT at position x 3
The electric field due to the intersection between the electrode finger 18 extending from 16 and the electrode finger 19 extending from the interdigital electrode 17 and the electric field due to the intersection between the electrode finger 20 extending from the interdigital electrode 16 and the electrode finger 19 extending from the interdigital electrode 17 are: , has a reverse phase with each other, since the surface acoustic wave the phase of the excitation at each intersection are opposite phases, position bending of the electrode fingers 19 and 20 suitably, cross two places at position x 3 By selecting the portion to be larger than the center wavelength of the surface acoustic wave propagating through the substrate, it is possible to realize a cross width capable of suppressing diffraction, and the same effect as in the first embodiment can be obtained. Further, the power distribution in the direction perpendicular to the surface acoustic wave propagation direction is also continuous, and better frequency characteristics can be obtained. In addition, the wiring routing process is simple, the effect of direct waves is suppressed, and the manufacturing process is simplified.
第８図は前記特開昭50−24050号に開示の技術よる出
力電極の構成図である。この電極は弾性表面波の伝搬方
向ｘに直角な方向について電力強度の分布がほぼ一様に
なるという利点を有するが、分割数が増えると交叉幅が
小さくなり回折効果を受けるという問題があった。ま
た、浮遊電極21が存在するため、浮遊電極の電位を算出
することにより所望の弾性表面波励振強度を与えること
が困難である。FIG. 8 is a block diagram of an output electrode according to the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 50-24050. This electrode has the advantage that the power intensity distribution is almost uniform in the direction perpendicular to the surface acoustic wave propagation direction x, but there is a problem that as the number of divisions increases, the cross width becomes smaller and the diffraction effect occurs. . Further, since the floating electrode 21 exists, it is difficult to calculate a potential of the floating electrode to give a desired surface acoustic wave excitation intensity.
第９図は本発明第７実施例の出力電極の平面図を示
す。破線で囲ったＣ部は基板１を伝わる弾性表面波の励
振強度が１対の対向電極指で励振しようとすると、電極
指交叉幅が表面波の中心波長よりも大きく其の２倍以下
となる部分である。Ｃ部においてすだれ状電極13と15に
より構成される交叉部は１対の対向電極指による場合と
同じ弾性表面波励振強度、電極指交叉幅を有する。ま
た、すだれ状電極13と14間は電極指が全て共通の電位と
なり、弾性表面波を励振しない。これにより、分割電極
部を選択する自由度が増し、製造工程，配線工程が簡略
化される。FIG. 9 is a plan view of an output electrode according to a seventh embodiment of the present invention. In the portion C surrounded by the broken line, when the excitation intensity of the surface acoustic wave transmitted through the substrate 1 is to be excited by a pair of counter electrode fingers, the electrode finger crossing width is larger than the center wavelength of the surface wave and is twice or less. Part. In the portion C, the crossing portion formed by the interdigital electrodes 13 and 15 has the same surface acoustic wave excitation strength and electrode finger crossing width as in the case of a pair of counter electrode fingers. Further, the electrode fingers all have a common potential between the interdigital electrodes 13 and 14, and do not excite surface acoustic waves. As a result, the degree of freedom in selecting the divided electrode portion is increased, and the manufacturing process and the wiring process are simplified.
さらに前記各実施例に示したような回折効果を抑圧す
ることにより帯域外を抑圧した本発明弾性表面波フィル
タを通信機器に利用すれば、S/N比が向上し、雑音の抑
圧度が向上する。Further, if the surface acoustic wave filter of the present invention, in which the out-of-band is suppressed by suppressing the diffraction effect as shown in each of the above embodiments, is used for communication equipment, the S / N ratio is improved, and the degree of noise suppression is improved. I do.
以上説明したように本発明によれば、所望弾性表面波
励振強度が小さい部分も、基板上を伝搬する弾性表面波
の波長よりも長い電極指交叉幅の励振源だけで実現する
ことが可能になり回折効果を抑圧することが出来るの
で、素子の周波数特性を向上させる効果が得られ、実施
例では従来例に比べ帯域外抑圧度が5dB改善された。As described above, according to the present invention, even a portion where the desired surface acoustic wave excitation intensity is small can be realized only by an excitation source having an electrode finger cross width longer than the wavelength of the surface acoustic wave propagating on the substrate. Since the diffraction effect can be suppressed, the effect of improving the frequency characteristics of the element can be obtained. In the embodiment, the degree of suppression outside the band is improved by 5 dB as compared with the conventional example.
第１図は本発明の第１実施例図、第２図は従来例図、第
３図は第２実施例図、第４図は第３実施例図、第５図は
第４実施例の出力電極図、第６図は第５実施例の出力電
極図、第７図は第６実施例の出力電極図、第８図は従来
の改良技術例図、第９図は第７実施例の出力電極図であ
る。 １……圧電性基板、２……入力すだれ状電極、3,3′…
…出力すだれ状電極、4,5……弾性表面波励振強度の小
さい位置の分割すだれ状電極、６……弾性表面波励振強
度の大きい位置のすだれ状電極、７……吸音材、8,8′
……入力端子、9,9′……出力端子、10,10′,11,11′,1
2……バスバー、13,13′,14,14′,15,15′,17……すだ
れ状電極、18,19,20……電極指、21……浮遊電極、Ａ…
…１電極指対で励振すると交叉幅が表面波中心波長より
短くなる部分、Ｂ……１電極指対で励振したとき交叉幅
が表面波中心波長より長くなる部分、ｘ……弾性表面波
伝搬方向軸、x1,x2,x3,x4……ｘ軸上の位置。1 is a diagram of a first embodiment of the present invention, FIG. 2 is a diagram of a conventional example, FIG. 3 is a diagram of a second embodiment, FIG. 4 is a diagram of a third embodiment, and FIG. FIG. 6 is an output electrode diagram of the fifth embodiment, FIG. 7 is an output electrode diagram of the sixth embodiment, FIG. 8 is a diagram of an example of an improved conventional technique, and FIG. 9 is a diagram of the seventh embodiment. It is an output electrode diagram. 1 ... Piezoelectric substrate, 2 ... Input interdigital electrode, 3,3 '...
... Output interdigital electrodes, 4, 5... Divided interdigital electrodes at positions where the surface acoustic wave excitation intensity is low, 6... Interdigital electrodes at positions where the surface acoustic wave excitation intensity is high, 7. ′
…… Input terminal, 9,9 ′ …… Output terminal, 10,10 ′, 11,11 ′, 1
2 busbar 13,13 ', 14,14', 15,15 ', 17 ... interdigital electrode, 18,19,20 ... electrode finger, 21 ... floating electrode, A ...
... A portion where the crossover width becomes shorter than the center wavelength of the surface wave when excited by one electrode finger pair, B. a portion where the crossover width becomes longer than the center wavelength of the surface wave when excited by one electrode finger pair, x... Direction axis, x 1 , x 2 , x 3 , x 4 ... Position on x axis.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 山田 純 神奈川県横浜市戸塚区吉田町292番地 株式会社日立製作所家電研究所内 (56)参考文献 特開 昭56−149818（ＪＰ，Ａ) ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Jun Yamada 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Home Appliance Research Laboratory, Hitachi, Ltd.
Claims (9)
数のすだれ状電極を設け、 それらの中の少なくとも１つの電極の電極指交差幅に重
み付けをした弾性表面波フィルタにおいて、所望の弾性
表面波励振強度を１対の通常の対向電極指で励振しよう
とすると、電極指交叉幅が小さく狭交叉幅となり、回折
効果の影響が出る位置で、表面波伝搬方向に直角な方向
で２箇所の表面波励振箇所を設け、各部分夫々の電極指
交差幅は表面波の中心波長よりも長く、夫々逆位相で励
振され、夫々の電極指交差幅の差が所望の弾性表面波励
振強度となるように形成した箇所を有することを特徴と
する弾性表面波フィルタ。1. A surface acoustic wave filter in which a plurality of interdigital electrodes used for input or output are provided on a piezoelectric substrate, and the electrode finger intersection width of at least one of the electrodes is weighted. When trying to excite the wave excitation intensity with a pair of normal counter electrode fingers, the electrode finger cross width is small and the cross width is narrow, and two points in the direction perpendicular to the surface wave propagation direction at the position where the diffraction effect is affected. A surface wave excitation point is provided, and the electrode finger intersection width of each part is longer than the center wavelength of the surface wave, and each part is excited in opposite phase, and the difference of each electrode finger intersection width becomes a desired surface acoustic wave excitation intensity. A surface acoustic wave filter having a portion formed as described above.
位置で所望の弾性表面波励振強度を１対の通常の対向電
極指で励振しようとすると、電極指交叉幅が小さく狭交
叉幅となり、回折効果の影響が出る場合に、その位置の
電極を、中間で表面波の伝搬方向に表面波中心波長の半
波長分だけ屈曲した電極指を備え、屈曲部により２分割
された各部分夫々の電極指交叉幅は表面波の中心波長よ
り長く、夫々逆位相で励振され、夫々の交叉幅の差が前
記狭交叉幅に等しくなるように形成したことを特徴とす
る請求項１記載の弾性表面波フィルタ。2. When a desired surface acoustic wave excitation intensity is to be excited by a pair of normal counter electrode fingers at a position of an electrode weighted with the electrode finger cross width, the electrode finger cross width becomes small and becomes narrow. In the case where the diffraction effect is exerted, the electrode at that position is provided with an electrode finger that is bent in the middle by a half wavelength of the center wavelength of the surface wave in the direction of propagation of the surface wave, and each of the portions is divided into two by the bent portion. 2. The elasticity according to claim 1, wherein the electrode finger crossing width is longer than the center wavelength of the surface wave, is excited in opposite phases, and the difference between the respective crossing widths is equal to the narrow crossing width. Surface wave filter.
の励振強度を得るには前記狭交叉幅とすべき隣接連続し
た複数位置に対し、表面波伝搬方向に直角な方向の中央
で表面波伝搬方向に延在する電極指共通母線で２分割さ
れたすだれ状電極を配置し、分割された各部分夫々の電
極指交叉幅は表面波の中心波長よりも長く、夫々逆位相
で励振され、夫々の電極指交叉幅の差が上記狭交叉幅に
等しくなるように形成した箇所を有することを特徴とす
る請求項１記載の弾性表面波フィルタ。3. A method for obtaining a desired excitation intensity of an electrode weighted with an electrode finger intersection width, wherein a plurality of adjacent continuous positions which should have the narrow intersection width have a surface at a center in a direction perpendicular to the surface acoustic wave propagation direction. An interdigitated electrode divided into two by an electrode finger common bus extending in the wave propagation direction is arranged, and the electrode finger intersection width of each of the divided portions is longer than the center wavelength of the surface wave, and they are excited in opposite phases. 2. The surface acoustic wave filter according to claim 1, further comprising a portion formed such that a difference between the electrode finger cross widths is equal to the narrow cross width.
表面波伝搬方向全長にわたって、最外側の電極指共通母
線が同電位になっていることを特徴とする請求項３記載
の弾性表面波フィルタ。4. The surface acoustic wave according to claim 3, wherein the outermost electrode finger common bus has the same potential over the entire length of the electrode in the surface acoustic wave propagation direction weighted to the electrode finger crossing width. filter.
を得ようとすると電極指交叉幅が表面波中心波長の２倍
よりも長くなる位置では、分割各部は、夫々の電極指交
叉幅が夫々表面中心波長より長く且つ各部交叉幅の和が
１対の対向電極指の場合の所要幅に等しく、夫々並列に
接続されて夫々同位相で励振され、（ロ）１対の対向電
極指で所望の励振強度を得ようとすると電極指交叉幅が
表面波中心波長よりも長く２倍以下となる位置では、分
割各部は、一方の部では上記１対の対向電極指の場合と
同じ電極指交叉幅で同じ位相で励振され、他方の部では
電極指交叉を無くして表面波は励振されず、（ハ）１対
の対向電極指で所望の励振強度を得ようとすると電極指
交叉幅が表面波中心波長以下となる位置では、分割各部
は、夫々の電極指交叉幅が表面波の中心波長より長く、
夫々逆位相で励振され、夫々の交叉幅の差が前記狭交叉
幅に等しくなるように、形成されていることを特徴とす
る請求項３記載の弾性表面波フィルタ。(5) When a desired excitation intensity is to be obtained with a pair of opposed electrode fingers, at a position where the electrode finger intersection width is longer than twice the center wavelength of the surface wave, each of the divided portions is provided with a respective electrode. The finger crossing width is longer than the center wavelength of the surface, and the sum of the crossing widths of the respective parts is equal to the required width in the case of a pair of opposing electrode fingers, and they are connected in parallel and are excited in the same phase, respectively. At a position where the electrode finger cross width is longer than the surface acoustic wave center wavelength and equal to or less than twice when the desired excitation intensity is to be obtained with the counter electrode finger, each of the divided portions is one of the above pair of counter electrode fingers. The same electrode finger cross width and the same phase are excited, and the other part eliminates the electrode finger crossing and the surface wave is not excited. (C) When a desired excitation intensity is obtained with a pair of opposing electrode fingers, At positions where the finger crossing width is equal to or smaller than the center wavelength of the surface wave, Or width is longer than the center wavelength of the surface wave,
4. The surface acoustic wave filter according to claim 3, wherein the surface acoustic wave filters are excited so as to be excited in opposite phases, respectively, so that a difference between the respective intersection widths is equal to the narrow intersection width.
において、（イ）１対の対向電極指で所望の励振強度を
得ようとすると電極指交叉幅が表面波中心波長の２倍よ
りも長くなる位置では、分割各部は、夫々の電極指交叉
幅が夫々表面中心波長より長く且つ各部交叉幅の和が１
対の対向電極指の場合の所要幅に等しく、夫々並列に接
続されて夫々同位相で励振されていることを特徴とする
請求項３記載の弾性表面波フィルタ。6. An interdigital transducer having the configuration according to claim 3, wherein (a) when an attempt is made to obtain a desired excitation intensity with a pair of opposing electrode fingers, the electrode finger crossing width is larger than twice the center wavelength of the surface wave. In the position where the distance is also longer, each of the divided portions has a crossover width of each electrode finger longer than the center wavelength of the surface, and the sum of the crossover widths of each portion is 1
4. The surface acoustic wave filter according to claim 3, wherein the width is equal to a required width in the case of a pair of counter electrode fingers, and each is connected in parallel and excited in the same phase.
において、（ロ）１対の対向電極指で所望の励振強度を
得ようとすると電極指交叉幅が表面波中心波長よりも長
く２倍以下となる位置では、分割各部は、一方の部では
上記１対の対向電極指の場合と同じ電極指交叉幅で同じ
位相で励振され、他方の部では電極指交叉を無くして表
面波を励振していることを特徴とする請求項３記載の弾
性表面波フィルタ。7. An interdigital transducer having the configuration according to claim 3, wherein (b) when an attempt is made to obtain a desired excitation intensity with a pair of opposing electrode fingers, the electrode finger crossing width is longer than the surface wave center wavelength. In the position where the width is equal to or less than twice, each of the divided portions is excited in the same phase at the same electrode finger crossing width as in the case of the pair of counter electrode fingers in one portion, and eliminates the electrode finger crossing in the other portion to reduce the surface wave. The surface acoustic wave filter according to claim 3, wherein the surface acoustic wave filter is excited.
ことを特徴とする請求項１〜７の何れか１項に記載の弾
性表面波フィルタ。8. The surface acoustic wave filter according to claim 1, wherein the interdigital transducer is of a split connector type.
面波フィルタを使用したことを特徴とする通信装置。9. A communication device using the surface acoustic wave filter according to any one of claims 1 to 8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1302103A JP2714189B2 (en) | 1989-11-22 | 1989-11-22 | Surface acoustic wave filter and communication device using the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1302103A JP2714189B2 (en) | 1989-11-22 | 1989-11-22 | Surface acoustic wave filter and communication device using the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03163904A JPH03163904A (en) | 1991-07-15 |
| JP2714189B2 true JP2714189B2 (en) | 1998-02-16 |
Family
ID=17904969
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1302103A Expired - Lifetime JP2714189B2 (en) | 1989-11-22 | 1989-11-22 | Surface acoustic wave filter and communication device using the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2714189B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4654271B2 (en) * | 2008-06-25 | 2011-03-16 | 日本電波工業株式会社 | Transversal filter |
| JP6411295B2 (en) * | 2014-10-16 | 2018-10-24 | 太陽誘電株式会社 | Elastic wave device, filter, and duplexer |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56149818A (en) * | 1980-04-23 | 1981-11-19 | Hitachi Ltd | Elastic surface wave device |
-
1989
- 1989-11-22 JP JP1302103A patent/JP2714189B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03163904A (en) | 1991-07-15 |
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