JPH09148873A - Three-electrode longitudinal mode resonator surface acoustic wave filter - Google Patents
Three-electrode longitudinal mode resonator surface acoustic wave filterInfo
- Publication number
- JPH09148873A JPH09148873A JP30420195A JP30420195A JPH09148873A JP H09148873 A JPH09148873 A JP H09148873A JP 30420195 A JP30420195 A JP 30420195A JP 30420195 A JP30420195 A JP 30420195A JP H09148873 A JPH09148873 A JP H09148873A
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- electrode
- central
- interdigitated
- center
- acoustic wave
- Prior art date
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- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】この発明は、縦モード共振器
型弾性表面波フィルタに関し、特に３つの入出力用交叉
指状電極を備えた３電極縦モード共振器型弾性表面波フ
ィルタに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a longitudinal mode resonator type surface acoustic wave filter, and more particularly to a three-electrode longitudinal mode resonator type surface acoustic wave filter having three input / output interdigital electrodes. .
【０００２】[0002]
【従来の技術】図６は従来の３電極縦モード共振器型弾
性表面波フィルタの平面図である。同図において、１’
は中央交叉指状電極（入力用交叉指状電極）、２−１お
よび２−２は中央交叉指状電極の両側に設けられた第１
および第２の交叉指状電極（第１および第２の出力用交
叉指状電極）、３−１および３−２は第１および第２の
グレーティング反射器であり、これらは圧電基板上に設
けられている。2. Description of the Related Art FIG. 6 is a plan view of a conventional three-electrode longitudinal mode resonator type surface acoustic wave filter. In the figure, 1 '
Is a central interdigital electrode (interdigital electrode for input), 2-1 and 2-2 are first electrodes provided on both sides of the central interdigital electrode.
And the second interdigitated electrodes (first and second interdigitated electrodes for output), 3-1 and 3-2 are the first and second grating reflectors, which are provided on the piezoelectric substrate. Has been.
【０００３】第１および第２のグレーティング反射器３
−１および３−２は、中央交叉指状電極１’の両側に、
第１および第２の交叉指状電極２−１および２−２を挟
んで設けられている。また、第１の交叉指状電極２−１
と第２の交叉指状電極２−２とは電気的に並列に接続さ
れており、中央交叉指状電極１’から励振された表面波
を検出する。グレーティング反射器３−１，３−２は中
央交叉指状電極１’から励振された表面波を反射する。First and second grating reflectors 3
-1 and 3-2 are provided on both sides of the central interdigitated electrode 1 ',
It is provided so as to sandwich the first and second interdigitated electrodes 2-1 and 2-2. In addition, the first interdigitated electrode 2-1
And the second interdigital electrode 2-2 are electrically connected in parallel, and the surface wave excited from the central interdigital electrode 1'is detected. The grating reflectors 3-1 and 3-2 reflect the surface wave excited from the central interdigital electrode 1 '.
【０００４】この３電極縦モード共振器型弾性表面波フ
ィルタでは、入出力用交叉指状電極のタップ数、および
入出力用交叉指状電極間距離、および交叉指状電極と反
射器間の距離を変えることにより、反射器間に生じる１
次および３次の共振モードをコントロールすることがで
き、フィルタの広帯域化および低損失を実現することが
できる。In this three-electrode longitudinal mode resonator type surface acoustic wave filter, the number of taps of the interdigitating electrode for input and output, the distance between the interdigitating electrode for input and output, and the distance between the interdigitating electrode and the reflector. 1 produced between the reflectors by changing the
The second and third resonance modes can be controlled, so that the filter can have a wide band and low loss.
【０００５】なお、この３電極縦モード共振器型弾性表
面波フィルタでは、中央交叉指状電極１’において、全
ての電極指の中心間距離はＬ／２（Ｌ：電極周期）とさ
れている（例えば、電子情報通信学会 論文誌「９００
ＭHz帯広帯域２重モードＳＡＷフィルタ Ｖｏｌ．Ｊ７
６−Ａ Ｎｏ．２ ｐｐ．２２７−２３５ １９９３年
２月）。In this three-electrode longitudinal mode resonator type surface acoustic wave filter, the center-to-center distance of all the electrode fingers in the central interdigital electrode 1'is L / 2 (L: electrode period). (For example, the Institute of Electronics, Information and Communication Engineers, "900
MHz band wide band dual mode SAW filter Vol. J7
6-A No. 2 pp. 227-235 February 1993).
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、従来の
３電極縦モード共振器型弾性表面波フィルタは、低損失
で広帯域なバンドパスフィルタを実現できるが、図７に
符号７１で示すように帯域近傍高域側の減衰量が１０ｄ
Ｂ以下と十分でない。その減衰量を改善させる方法とし
て、入出力用交叉指状電極のタップ数を増やす方法があ
るが、通過帯域幅が狭くなってしまい必要帯域が確保で
きなくなってしまう。また、従来の構成のままで入出力
用交叉指状電極間距離、交叉指状電極と反射器との距離
を変え各共振モードをコントロールする方法では、帯域
内振幅偏差が大きくなってしまう等の問題が生じる。However, the conventional three-electrode longitudinal mode resonator type surface acoustic wave filter can realize a bandpass filter having a low loss and a wide band. However, as shown by reference numeral 71 in FIG. High-side attenuation is 10d
It is not enough as B or less. As a method of improving the attenuation amount, there is a method of increasing the number of taps of the interdigital finger electrodes for input and output, but the pass band width becomes narrow and the necessary band cannot be secured. Further, in the method of controlling each resonance mode by changing the distance between the interdigitating electrodes for input and output and the distance between the interdigitating electrodes and the reflector with the conventional configuration, the in-band amplitude deviation becomes large. The problem arises.
【０００７】本発明はこのような課題を解決するために
なされたもので、その目的とするところは、帯域内特性
を劣化させることなく、帯域近傍高域側の減衰量を向上
させることの可能な３電極縦モード共振器型弾性表面波
フィルタを提供することにある。The present invention has been made in order to solve such a problem, and an object of the present invention is to improve the attenuation amount in the high band near the band without deteriorating the in-band characteristics. Another object is to provide a three-electrode longitudinal mode resonator type surface acoustic wave filter.
【０００８】[0008]
【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、第１発明（請求項１に係る発明）は、上述し
た３電極縦モード共振器型弾性表面波フィルタにおい
て、中央交叉指状電極を第１の中央交叉指状電極と第２
の中央交叉指状電極とに２分割し、この第１の中央交叉
指状電極と第２の中央交叉指状電極とを電気的に並列に
接続し、かつこの第１の中央交叉指状電極と第２の中央
交叉指状電極との互いに最も近接する電極指の中心間距
離を所定の範囲としたものである。この発明によれば、
中央交叉指状電極が２分割され、この２分割された各電
極が並列に接続され、かつこの各電極の互いに最も近接
する電極指の中心間距離が所定の範囲とされる。In order to achieve such an object, the first invention (the invention according to claim 1) is the center crossing finger in the above-mentioned three-electrode longitudinal mode resonator type surface acoustic wave filter. The electrode is the first central interdigitated electrode and the second electrode
And the central central interdigital electrode is electrically connected in parallel to the first central interdigital electrode, and the first central interdigital electrode is connected to the first central interdigital electrode. The distance between the centers of the electrode fingers closest to each other and the second central cross-finger electrode is within a predetermined range. According to the invention,
The central cross-finger electrode is divided into two, each of the two divided electrodes is connected in parallel, and the center-to-center distance between the electrode fingers of these electrodes that are closest to each other is within a predetermined range.
【０００９】第２発明（請求項２に係る発明）は、第１
発明において、第１の中央交叉指状電極と第２の中央交
叉指状電極との互いに最も近接する電極指の中心間距離
ＡＬ１を、０．５５×Ｌ≦ＡＬ１≦０．８５×Ｌ（Ｌ：
電極周期）の範囲としたものである。この発明によれ
ば、中央交叉指状電極が２分割され、この２分割された
各電極が並列に接続され、かつこの各電極の互いに最も
近接する電極指の中心間距離ＡＬ１が０．５５×Ｌ≦Ａ
Ｌ１≦０．８５×Ｌの範囲とされる。The second invention (the invention according to claim 2) is the first invention.
In the invention, the center-to-center distance AL1 of the electrode fingers closest to each other between the first central interdigitated electrode and the second central interdigitated electrode is set to 0.55 × L ≦ AL1 ≦ 0.85 × L (L :
Electrode period). According to the present invention, the central interdigitated electrode is divided into two, the divided two electrodes are connected in parallel, and the center-to-center distance AL1 of the electrode fingers of the respective electrodes that are closest to each other is 0.55 ×. L ≦ A
The range is L1 ≦ 0.85 × L.
【００１０】第３発明（請求項３に係る発明）は、中央
交叉指状電極と、この中央交叉指状電極の両側に設けら
れた第１および第２の交叉指状電極と、中央交叉指状電
極の両側に第１および第２の交叉指状電極を挟んで設け
られた第１および第２の反射器とを２段構成として圧電
基板上に設け、１段目の第１および第２の交叉指状電極
と２段目の第１および第２の交叉指状電極とを電気的に
縦続接続し、また各段の中央交叉指状電極を第１の中央
交叉指状電極と第２の中央交叉指状電極とに２分割し、
この各段の第１の中央交叉指状電極と第２の中央交叉指
状電極とを電気的に並列に接続し、かつこの各段の第１
の中央交叉指状電極と第２の中央交叉指状電極との互い
に最も近接する電極指の中心間距離を所定の範囲とした
ものである。この発明によれば、各段の中央交叉指状電
極が２分割され、この２分割された各段の各電極が並列
に接続され、かつこの各段の各電極の互いに最も近接す
る電極指の中心間距離が所定の範囲とされる。A third invention (an invention according to claim 3) is a central interdigital electrode, first and second interdigital electrodes provided on both sides of the central interdigital electrode, and a central interdigital electrode. A first electrode and a second reflector provided on both sides of the first electrode and a second interdigital electrode sandwiching the first electrode and the second reflector on the piezoelectric substrate in a two-stage configuration. Electrically connecting the first and second interdigitated electrodes of the second stage to the second interdigitated electrode, and the central interdigitated electrode of each stage is connected to the first central interdigitated electrode and the second interdigitated electrode. And the central interdigitated electrode of
The first central interdigitated electrode and the second central interdigitated electrode of each stage are electrically connected in parallel, and the first central interdigitated electrode of each stage is electrically connected in parallel.
The center-to-center distance between the electrode fingers that are closest to each other between the central cross-finger electrode and the second central cross-finger electrode is within a predetermined range. According to the present invention, the central interdigitated electrode of each stage is divided into two, the respective electrodes of the respective stages divided into two are connected in parallel, and the electrode fingers of the electrodes of the respective stages which are closest to each other are connected. The center-to-center distance is within a predetermined range.
【００１１】第４発明（請求項４に係る発明）は、第３
発明において、各段の第１の中央交叉指状電極と第２の
中央交叉指状電極との互いに最も近接する電極指の中心
間距離ＡＬ１を、０．５５×Ｌ≦ＡＬ１≦０．８５×Ｌ
（Ｌ：電極周期）の範囲としたものである。各段の中央
交叉指状電極が２分割され、この２分割された各段の各
電極が並列に接続され、かつこの各段の各電極の互いに
最も近接する電極指の中心間距離ＡＬ１が０．５５×Ｌ
≦ＡＬ１≦０．８５×Ｌの範囲とされる。The fourth invention (the invention according to claim 4) is the third invention.
In the present invention, the center-to-center distance AL1 of the electrode fingers that are closest to each other between the first central interdigitated electrode and the second central interdigitated electrode in each step is 0.55 × L ≦ AL1 ≦ 0.85 × L
The range is (L: electrode period). The central interdigitated electrode of each stage is divided into two, the divided electrodes of each stage are connected in parallel, and the center-to-center distance AL1 of the electrode fingers closest to each other of each stage is 0. .55 x L
The range is ≦ AL1 ≦ 0.85 × L.
【００１２】[0012]
【発明の実施の形態】以下、本発明を実施の形態に基づ
き詳細に説明する。 〔実施の形態１：第１発明，第２発明〕図１はこの発明
の一実施の形態を示す平面図である。同図において、図
６と同一符号は同一あるいは同等構成要素を示し、その
説明は省略する。この実施の形態では、中央交叉指状電
極１を第１の中央交叉指状電極１−１と第２の中央交叉
指状電極１−２とに２分割し、この第１の中央交叉指状
電極１−１と第２の中央交叉指状電極１−２とを電気的
に並列に接続し、かつこの第１の中央交叉指状電極１−
１と第２の中央交叉指状電極１−２との互いに最も近接
する電極指の中心間距離ＡＬ１を、０．５５×Ｌ≦ＡＬ
１≦０．８５×Ｌ（Ｌ：電極周期）の範囲としている。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail based on embodiments. [Embodiment 1: First Invention, Second Invention] FIG. 1 is a plan view showing an embodiment of the present invention. In the figure, the same reference numerals as in FIG. In this embodiment, the central interdigitated electrode 1 is divided into a first central interdigitated electrode 1-1 and a second central interdigitated electrode 1-2, and the first central interdigitated electrode 1 is divided into two parts. The electrode 1-1 and the second central interdigitating electrode 1-2 are electrically connected in parallel, and the first central interdigitating electrode 1-
The distance AL1 between the centers of the electrode fingers of the first and second central interdigitated electrodes 1-2 that are closest to each other is 0.55 × L ≦ AL.
The range is 1 ≦ 0.85 × L (L: electrode period).
【００１３】次に、この実施の形態において、帯域近傍
高域側の減衰量を向上させることができる点について説
明する。Next, in this embodiment, the point that the amount of attenuation on the high frequency side near the band can be improved will be described.
【００１４】この実施の形態の構成で、第１の中央交叉
指状電極１−１と第２の中央交叉指状電極１−２との互
いに最も近接する電極指の中心間距離ＡＬ１をＡＬ１＝
０．５Ｌとした場合、図３（ａ）に示すように、その伝
送特性に反射器間の共振モード３１、入出力用交叉指状
電極間の共振モード３２が現れる。中心間距離ＡＬ１を
変え、０．５５×Ｌ≦ＡＬ１≦０．８５×Ｌの範囲とす
ると、図３（ｂ）に示すように、各共振モードはそれぞ
れ３１’，３２’となる。その共振モードのうち反射器
間の共振モード３１のみ共振周波数が顕著に低下して行
き、帯域内特性を劣化させることなく、また反射器間の
共振モードの低下の影響で帯域近傍高域側の減衰量３３
を向上させることが可能となる。With the configuration of this embodiment, the center distance AL1 between the first central interdigitated electrode 1-1 and the second central interdigitated electrode 1-2 that are closest to each other is AL1 =
In the case of 0.5 L, as shown in FIG. 3A, a resonance mode 31 between the reflectors and a resonance mode 32 between the input and output interdigital electrodes appear in the transmission characteristics. If the center-to-center distance AL1 is changed to a range of 0.55 × L ≦ AL1 ≦ 0.85 × L, the resonance modes are 31 ′ and 32 ′, respectively, as shown in FIG. 3B. Among the resonance modes, only the resonance mode 31 between the reflectors significantly decreases the resonance frequency, without deteriorating the in-band characteristics, and due to the decrease in the resonance mode between the reflectors, the resonance frequency of the high frequency side near the band is high. Attenuation 33
Can be improved.
【００１５】図４に中心間距離ＡＬ１と帯域内振幅偏差
および帯域近傍高域側減衰量との関係を示す。同図よ
り、０．５５×Ｌ≦ＡＬ１≦０．８５×Ｌの範囲が、帯
域内振幅偏差１ｄＢ以下、帯域近傍高域側減衰量１０ｄ
Ｂ以上を実現できる最適な範囲であることが分かる。FIG. 4 shows the relationship between the center-to-center distance AL1 and the in-band amplitude deviation and the amount of attenuation in the high band near the band. From the figure, the range of 0.55 × L ≦ AL1 ≦ 0.85 × L is within the band amplitude deviation of 1 dB or less, and the attenuation near the band in the high frequency range is 10 d.
It can be seen that this is the optimum range in which B or higher can be realized.
【００１６】図２はこの実施の形態における伝送特性の
計算値を示す図である。図７に示した従来の伝送特性の
計算値と比較して分かるように、この実施の形態では帯
域近傍高域側の減衰量２１を従来の減衰量７１に対して
３ｄＢ以上向上させることが可能となる。FIG. 2 is a diagram showing calculated values of transmission characteristics in this embodiment. As can be seen by comparing with the calculated values of the conventional transmission characteristics shown in FIG. 7, in this embodiment, the attenuation amount 21 on the high frequency side near the band can be improved by 3 dB or more as compared with the conventional attenuation amount 71. Becomes
【００１７】〔実施の形態２：第３発明，第４発明〕図
５はこの発明の別の実施の形態を示す平面図である。こ
の実施の形態では、中央交叉指状電極１と、この中央交
叉指状電極１の両側に設けられた第１の交叉指状電極２
−１および第２の交叉指状電極２−２と、中央交叉指状
電極１の両側に第１の交叉指状電極２−１および第２の
交叉指状電極２−２を挟んで設けられた第１のグレーテ
ィング反射器３−１および第２のグレーティング反射器
３−２とを２段構成として圧電基板上に設けている。[Second Embodiment: Third Invention and Fourth Invention] FIG. 5 is a plan view showing another embodiment of the present invention. In this embodiment, the central interdigital electrode 1 and the first interdigital electrodes 2 provided on both sides of the central interdigital electrode 1 are arranged.
-1 and the second interdigital electrode 2-2, and the first interdigital electrode 2-1 and the second interdigital electrode 2-2 are provided on both sides of the central interdigital electrode 1 with the first interdigital electrode 2-1 and the second interdigital electrode 2-2 interposed therebetween. Further, the first grating reflector 3-1 and the second grating reflector 3-2 are provided on the piezoelectric substrate in a two-stage configuration.
【００１８】そして、１段目の第１の交叉指状電極２−
１(1) および第２の交叉指状電極２−２(1) と２段目の
第１の交叉指状電極２−１(2) および第２の交叉指状電
極２−２(2) とを電気的に縦続接続し、また各段の中央
交叉指状電極１(1) ，１(2)を第１の中央交叉指状電極
１−１(1) ，１−１(2) と第２の中央交叉指状電極１−
２(1) ，１−２(2) とに２分割し、この各段の第１の中
央交叉指状電極１−１(1) ，１−１(2) と第２の中央交
叉指状電極１−２(1) ，１−２(2) とを電気的に並列に
接続し、かつこの各段の第１の中央交叉指状電極１−１
(1) ，１−１(2 ) と第２の中央交叉指状電極１−２
(1) ，１−２(2) との互いに最も近接する電極指の中心
間距離ＡＬ１を、０．５５×Ｌ≦ＡＬ１≦０．８５×Ｌ
（Ｌ：電極周期）の範囲としている。The first interdigitated electrode 2- of the first stage
1 (1) and the second interdigitated electrode 2-2 (1) and the first interdigitated electrode 2-1 (2) and the second interdigitated electrode 2-2 (2) of the second stage Are electrically connected in cascade, and the central interdigitated electrodes 1 (1) , 1 (2) of each stage are connected to the first central interdigitated electrodes 1-1 (1) , 1-1 (2) . Second central interdigitated electrode 1-
2 (1) , 1-2 (2) divided into two, and the first central interdigitated electrodes 1-1 (1) , 1-1 (2) and the second central interdigitated electrode of each stage The electrodes 1-2 (1) and 1-2 (2) are electrically connected in parallel, and the first central interdigitated electrode 1-1 of each stage is provided.
(1) , 1-1 (2 ) and the second central interdigitated electrode 1-2
(1) , 1-2 (2) The center-to-center distance AL1 of the electrode fingers closest to each other is 0.55 × L ≦ AL1 ≦ 0.85 × L
The range is (L: electrode period).
【００１９】このような構成とすることで、挿入損失は
倍になるが、帯域外減衰量も倍となるため、帯域内近傍
高域側減衰量は従来に比べ６ｄＢ以上向上する。With such a configuration, the insertion loss is doubled, but the out-of-band attenuation is also doubled, so that the in-band vicinity high-frequency side attenuation is improved by 6 dB or more as compared with the conventional case.
【００２０】なお、参考として、既に米国特許として成
立している類似の特許と発表されている関連論文につい
て、本発明との違いを明らかにしておく。米国特許#4,6
16,197（P.V.Wright,"Resonator",US Patent #4,616,19
7,October7,1986）およびP.V.Wrightの論文（1992 Ultr
asonics Symposium"A review ofsaw resonator filter
technology"P.V.Wright）では、中央部に電極指のない
Ｌ／４以上（電極指間距離ではＬ／２以上、Ｌ：電極周
期）の領域（以下、キャビティと呼ぶ）を有する交叉指
状電極を使用した共振子や２つの交叉指状電極と反射器
とで構成した２電極縦モード共振器型フィルタに応用し
た例を挙げている。As a reference, the difference from the present invention will be clarified with respect to the related papers which have been announced as similar patents already established as US patents. US Patent # 4,6
16,197 (PVWright, "Resonator", US Patent # 4,616,19
7, October7,1986) and PV Wright's paper (1992 Ultr
asonics Symposium "A review of saw resonator filter
In technology "PVWright", the interdigitated electrode having a region of L / 4 or more (L / 2 or more in the distance between the electrode fingers, L: electrode cycle) (hereinafter referred to as a cavity) with no electrode fingers in the central portion is used. In this example, the present invention is applied to a two-electrode longitudinal mode resonator type filter composed of a resonator and two interdigital electrodes and a reflector.
【００２１】しかしながら、共振子では、交叉指状電極
の中央部にキャビティを設けることで交叉指状電極の中
央部に音響エネルギーが集中せず分散するため共振子の
低ロス化が図れるという内容であり、本発明が複数の共
振モードを利用するフィルタである点で異なっている。
また、P.V.Wrightの論文によると、２電極構成のフィル
タでは２電極のうち片方を分割電極とするため、このフ
ィルタは中央からみて非対称な構造となり、それにより
不要スプリアスモードが生じる欠点がある。これに対
し、本発明の３電極縦モード共振器型弾性表面波フィル
タは、中央交叉指状電極を分割してもフィルタ構造の対
称性は崩れないため、不要スプリアスモードが生じない
利点を有する。However, in the resonator, by providing a cavity in the central portion of the interdigital electrode, acoustic energy is not concentrated in the central portion of the interdigital electrode and is dispersed, so that the loss of the resonator can be reduced. Yes, there is a difference in that the present invention is a filter utilizing a plurality of resonance modes.
According to PV Wright's paper, a filter having a two-electrode structure has one of two electrodes as a split electrode, so that this filter has an asymmetrical structure when viewed from the center, which causes a disadvantage of generating an unnecessary spurious mode. On the other hand, the three-electrode longitudinal mode resonator type surface acoustic wave filter of the present invention has an advantage that unnecessary spurious modes do not occur because the symmetry of the filter structure is not broken even when the central interdigital electrode is divided.
【００２２】[0022]
【発明の効果】以上説明したことから明らかなように本
発明によれば、中央交叉指状電極を２分割し、この２分
割した各電極を並列に接続し、かつこの各電極の互いに
最も近接する電極指の中心間距離を所定の距離範囲とす
ることにより、従来の入出力交叉指状電極のタップ数
や、入出力交叉指状電極間距離、交叉指状電極と反射器
間の距離を変えることでは実現できなかった、帯域内特
性を劣化させることく、帯域近傍高域側の減衰量を向上
させることが可能となる。As is apparent from the above description, according to the present invention, the central interdigital electrode is divided into two, the divided electrodes are connected in parallel, and the respective electrodes are closest to each other. By setting the distance between the centers of the electrode fingers to be within a predetermined distance range, the number of taps of the conventional input / output interdigital electrode, the distance between the input / output interdigital electrode, and the distance between the interdigital electrode and the reflector can be adjusted. It is possible to improve the attenuation amount on the high frequency side near the band without deteriorating the in-band characteristic, which could not be realized by changing it.
【図１】 本発明の一実施の形態（実施の形態１）を示
す平面図である。FIG. 1 is a plan view showing an embodiment (Embodiment 1) of the present invention.
【図２】 この実施の形態における伝送特性の計算値を
示す図である。FIG. 2 is a diagram showing calculated values of transmission characteristics in this embodiment.
【図３】 この実施の形態において帯域近傍高域側の減
衰量を向上させることができることを説明するための図
である。FIG. 3 is a diagram for explaining that the attenuation amount on the high frequency side near the band can be improved in this embodiment.
【図４】 中心間距離ＡＬ１と帯域内振幅偏差および帯
域近傍高域側減衰量との関係を示す図である。FIG. 4 is a diagram showing a relationship between a center-to-center distance AL1 and an in-band amplitude deviation and a band-side high-frequency side attenuation amount.
【図５】 本発明の別の実施の形態（実施の形態２）を
示す平面図である。FIG. 5 is a plan view showing another embodiment (Embodiment 2) of the present invention.
【図６】 従来の３電極縦モード共振器型弾性表面波フ
ィルタの平面図である。FIG. 6 is a plan view of a conventional three-electrode longitudinal mode resonator type surface acoustic wave filter.
【図７】 従来の３電極縦モード共振器型弾性表面波フ
ィルタにおける伝送特性の計算値を示す図である。FIG. 7 is a diagram showing calculated values of transmission characteristics in a conventional three-electrode longitudinal mode resonator type surface acoustic wave filter.
１…中央交叉指状電極、１−１…第１の中央交叉指状電
極、１−２…第２の中央交叉指状電極、２−１…第１の
交叉指状電極、２−２…第２の交叉指状電極、３−１…
第１のグレーティング反射器、３−２…第２のグレーテ
ィング反射器、Ｌ…電極周期、ＡＬ１…中心間距離。DESCRIPTION OF SYMBOLS 1 ... Central interdigitated electrode, 1-1 ... 1st central interdigitated electrode, 1-2 ... 2nd central interdigitated electrode, 2-1 ... 1st interdigitated electrode, 2-2 ... Second interdigitated electrode 3-1 ...
1st grating reflector, 3-2 ... 2nd grating reflector, L ... electrode period, AL1 ... center distance.
Claims (4)
電極の両側に設けられた第１および第２の交叉指状電極
と、前記中央交叉指状電極の両側に前記第１および第２
の交叉指状電極を挟んで設けられた第１および第２の反
射器とを圧電基板上に備えてなる３電極縦モード共振器
型弾性表面波フィルタにおいて、 前記中央交叉指状電極が第１の中央交叉指状電極と第２
の中央交叉指状電極とに２分割され、 この第１の中央交叉指状電極と第２の中央交叉指状電極
とが電気的に並列に接続され、 かつこの第１の中央交叉指状電極と第２の中央交叉指状
電極との互いに最も近接する電極指の中心間距離が所定
の範囲とされていることを特徴とする３電極縦モード共
振器型弾性表面波フィルタ。1. A central interdigitated electrode, first and second interdigitated electrodes provided on both sides of the central interdigitated electrode, and the first and second interdigitated electrodes disposed on both sides of the central interdigitated electrode. Two
A three-electrode longitudinal mode resonator type surface acoustic wave filter comprising a piezoelectric substrate and first and second reflectors sandwiching the interdigitated electrode between the central interdigitated electrode Center interdigitated electrode and second
And the first central cross-finger electrode is electrically connected in parallel, and the first central cross-finger electrode is divided into two. A three-electrode longitudinal mode resonator type surface acoustic wave filter, characterized in that the center-to-center distance between the electrode fingers closest to each other and the second central cross-finger electrode is within a predetermined range.
電極と第２の中央交叉指状電極との互いに最も近接する
電極指の中心間距離をＡＬ１，電極周期をＬとしたと
き、その中心間距離ＡＬ１が０．５５×Ｌ≦ＡＬ１≦
０．８５×Ｌの範囲とされていることを特徴とする３電
極縦モード共振器型弾性表面波フィルタ。2. The method according to claim 1, wherein a distance between the centers of the electrode fingers closest to each other between the first central interdigitated electrode and the second central interdigitated electrode is AL1 and an electrode period is L, The center-to-center distance AL1 is 0.55 × L ≦ AL1 ≦
A three-electrode longitudinal mode resonator type surface acoustic wave filter having a range of 0.85 × L.
電極の両側に設けられた第１および第２の交叉指状電極
と、前記中央交叉指状電極の両側に前記第１および第２
の交叉指状電極を挟んで設けられた第１および第２の反
射器とを２段構成として圧電基板上に備えてなる３電極
縦モード共振器型弾性表面波フィルタであって、 １段目の第１および第２の交叉指状電極と２段目の第１
および第２の交叉指状電極とが電気的に縦続接続され、 また各段の中央交叉指状電極が第１の中央交叉指状電極
と第２の中央交叉指状電極とに２分割され、 この各段の第１の中央交叉指状電極と第２の中央交叉指
状電極とが電気的に並列に接続され、 かつこの各段の第１の中央交叉指状電極と第２の中央交
叉指状電極との互いに最も近接する電極指の中心間距離
が所定の範囲とされていることを特徴とする３電極縦モ
ード共振器型弾性表面波フィルタ3. A central interdigitated electrode, first and second interdigitated electrodes provided on both sides of the central interdigitated electrode, and first and second electrodes disposed on both sides of the central interdigitated electrode. Two
A three-electrode longitudinal mode resonator type surface acoustic wave filter comprising a first and a second reflector provided on both sides of the interdigitated electrode in a two-stage configuration on a piezoelectric substrate, the first stage First and second interdigitated electrodes and the first of the second stage
And the second interdigital electrode are electrically connected in cascade, and the central interdigital electrode of each stage is divided into a first central interdigital electrode and a second central interdigital electrode, The first central cross-finger electrode and the second central cross-finger electrode of each stage are electrically connected in parallel, and the first central cross-finger electrode and the second central cross-finger electrode of each stage are connected. A three-electrode longitudinal mode resonator type surface acoustic wave filter characterized in that the center-to-center distance between the electrode fingers closest to each other with the finger-like electrode is within a predetermined range.
叉指状電極と第２の中央交叉指状電極との互いに最も近
接する電極指の中心間距離をＡＬ１，電極周期をＬとし
たとき、その中心間距離ＡＬ１が０．５５×Ｌ≦ＡＬ１
≦０．８５×Ｌの範囲とされていることを特徴とする３
電極縦モード共振器型弾性表面波フィルタ。4. The distance between the centers of the electrode fingers closest to each other of the first central interdigitated electrode and the second central interdigitated electrode of each step is AL1, and the electrode period is L. Then, the center-to-center distance AL1 is 0.55 × L ≦ AL1
≦ 0.85 × L range 3
Electrode longitudinal mode resonator type surface acoustic wave filter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7304201A JP3039341B2 (en) | 1995-11-22 | 1995-11-22 | Three-electrode longitudinal mode resonator type surface acoustic wave filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7304201A JP3039341B2 (en) | 1995-11-22 | 1995-11-22 | Three-electrode longitudinal mode resonator type surface acoustic wave filter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09148873A true JPH09148873A (en) | 1997-06-06 |
| JP3039341B2 JP3039341B2 (en) | 2000-05-08 |
Family
ID=17930240
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7304201A Expired - Lifetime JP3039341B2 (en) | 1995-11-22 | 1995-11-22 | Three-electrode longitudinal mode resonator type surface acoustic wave filter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3039341B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6762657B2 (en) | 2000-04-18 | 2004-07-13 | Murata Manufacturing Co., Ltd. | Longitudinally coupled resonator-type surface acoustic wave filter |
| WO2016087106A1 (en) * | 2014-12-05 | 2016-06-09 | Epcos Ag | Arrangement comprising a dms filter and a steep right edge |
-
1995
- 1995-11-22 JP JP7304201A patent/JP3039341B2/en not_active Expired - Lifetime
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6762657B2 (en) | 2000-04-18 | 2004-07-13 | Murata Manufacturing Co., Ltd. | Longitudinally coupled resonator-type surface acoustic wave filter |
| WO2016087106A1 (en) * | 2014-12-05 | 2016-06-09 | Epcos Ag | Arrangement comprising a dms filter and a steep right edge |
| CN107005218A (en) * | 2014-12-05 | 2017-08-01 | 追踪有限公司 | Device with DMS wave filters and precipitous right belt side |
| US10340884B2 (en) | 2014-12-05 | 2019-07-02 | Snaptrack, Inc. | Arrangement comprising a DMS filter and a steep right edge |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3039341B2 (en) | 2000-05-08 |
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