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JPH0865097A - Surface acoustic wave filter device - Google Patents

Surface acoustic wave filter device

Info

Publication number
JPH0865097A
JPH0865097A JP19545494A JP19545494A JPH0865097A JP H0865097 A JPH0865097 A JP H0865097A JP 19545494 A JP19545494 A JP 19545494A JP 19545494 A JP19545494 A JP 19545494A JP H0865097 A JPH0865097 A JP H0865097A
Authority
JP
Japan
Prior art keywords
resonator
idt
reflectors
surface acoustic
acoustic wave
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.)
Withdrawn
Application number
JP19545494A
Other languages
Japanese (ja)
Inventor
Satoshi Ichikawa
聡 市川
Yasushi Kuroda
泰史 黒田
Masayoshi Etsuno
昌芳 越野
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toshiba Corp
Original Assignee
Toshiba Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Toshiba Corp filed Critical Toshiba Corp
Priority to JP19545494A priority Critical patent/JPH0865097A/en
Publication of JPH0865097A publication Critical patent/JPH0865097A/en
Withdrawn legal-status Critical Current

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  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)

Abstract

PURPOSE: To reconcile sufficient band widths and out-of-band attenuation amount by adding a notch filter composed of at least one or more resonators to at least one of the input/output of an interdigital transducer (IDT) serially and in parallel. CONSTITUTION: IDT11 to 13 having reflectors Gr 7 and Gr 8 on the both sides are arranged in a horizontal line on a substrate. The electric signals inputted from a pad 1 pass a serial/parallel resonator, the signals are transmitted to the IDT 11 and the IDT 13, and the surface acoustic waves excited by these IDT are received in the IDT 12 at the center. The pad 1 is serially connected with a resonator (I) and a resonator (II) and the pad 1 is further connected with a resonator (III) in parallel. In this stage, the resonator (I) is composed of reflectors Gr 9 and Gr 10 and the IDT 14 held by the reflectors, the resonator (II) is composed of reflectors Gr 9a and Gr 10a and the IDT 15 held by the reflectors, and the resonator (III) is composed of reflectors Gr 9b and Gr 10 and the IDT 16 held by the reflectors.

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【産業上の利用分野】本発明は弾性表面波を用いた移動
体通信用フィルタ装置に関わり、とくに共振子型構成を
とる弾性表面波フィルタ装置に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication filter device using surface acoustic waves, and more particularly to a surface acoustic wave filter device having a resonator type structure.

【0002】[0002]

【従来の技術】近年、電波を利用する電子機器のフイル
タ、遅延線、発振器等の素子として、多くの弾性表面波
装置が用いられている。とくに、小型・軽量でかつフイ
ルタとしての急峻遮断性能が高い弾性表面波フィルタ装
置は、移動体通信分野において、携帯端末装置の RF 段
および IF 段のフイルタとして多用されるようになって
きており、外部でチューニングすることなく必要とする
広い通過帯域で低損失を実現し、通過帯域外においては
急峻かつ充分に減衰する高性能なことが要求されてい
る。
2. Description of the Related Art In recent years, many surface acoustic wave devices have been used as elements such as filters, delay lines, and oscillators of electronic equipment that uses radio waves. In particular, surface acoustic wave filter devices, which are small and lightweight and have high sharp cutoff performance as filters, have come to be widely used as RF stage and IF stage filters for mobile terminal devices in the mobile communication field. It is required that a low loss be realized in a wide pass band required without external tuning, and that the high performance be steep and sufficiently attenuated outside the pass band.

【0003】自動車電話用やその他の移動体通信に用い
られる弾性表面波フィルタの構成としては共振子を梯子
状に接続した LADDER 型、くし形変換器(以下、IDT と
略称)を複数個並べた IIDT 型、数個のIDT を両側で反
射器で挟んだ共振子型などが用いられている。とくに帯
域外抑圧度を重視した場合、フイルタの入出力インピー
ダンスを 50 Ωにあわせたい場合などに共振子型フイル
タ構造とすることが多い。 自動車電話用やその他の移
動体通信に用いられる弾性表面波フィルタの構成として
は共振子を梯子状に接続した LADDER 型、くし形変換器
(以下、IDT と略称)を複数個並べた IIDT 型、数個の
IDT を両側で反射器で挟んだ共振子型などが用いられて
いる。とくに帯域外抑圧度を重視した場合、フイルタの
入出力インピーダンスを 50 Ωにあわせたい場合などに
共振子型フイルタ構造とすることが多い。
As a structure of a surface acoustic wave filter used for mobile telephones and other mobile communications, a plurality of LADDER type comb-shaped transducers (hereinafter abbreviated as IDT) in which resonators are connected in a ladder are arranged. The IIDT type and the resonator type in which several IDTs are sandwiched between reflectors are used. In particular, when the degree of out-of-band suppression is emphasized, a resonator-type filter structure is often used to match the input / output impedance of the filter to 50 Ω. The surface acoustic wave filters used for mobile phones and other mobile communications are composed of a LADDER type with resonators connected in a ladder, an IIDT type with multiple comb transducers (hereinafter abbreviated as IDTs) arranged, Several
A resonator type is used in which the IDT is sandwiched by reflectors on both sides. In particular, when the degree of out-of-band suppression is emphasized, a resonator-type filter structure is often used to match the input / output impedance of the filter to 50 Ω.

【0004】従来の共振子型フイルタ構成を図9および
図11により説明する。図9は、共振子型フイルタ構造
のなかでも帯域外減衰量を向上させるため鏡面対称に 2
つの共振子型フイルタを接続してある。また図11は 1
段構成の共振子型フイルタを示す。 図9において、パ
ッド1は入力信号端子に接続され、パッド2、3は入力
側の接地(以下、 GNDと略称)におとされている。パッ
ド1、3にて IDT12に電気信号が入力されると圧電性
基板上に弾性表面波が発生し、これは IDT11、 IDT1
3によって受けられ再度電気信号に変わる。この電気信
号が IDT11a、 IDT13aによって再び弾性表面波と
なり、最後に IDT12aにて受けとられ電気信号に変換
された後、パッド6を介して出力信号端子へ出力され
る。パッド4、5は出力側 GNDに接続され、入出力 GND
は互いに接続され共通の電位となっている。なお、 IDT
11、 IDT13の外側に反射器7および8が、 IDT11
a、IDT13aの外側に反射器7aおよび8aがそれぞ
れ配設されている。この構成で得られた周波数特性を図
10に示す。また、図11に示す 1段構成の共振子型フ
イルタで得られた周波数特性を図12に示す。
A conventional resonator type filter structure will be described with reference to FIGS. 9 and 11. Fig. 9 shows a mirror symmetry in order to improve the out-of-band attenuation in the resonator filter structure.
Two resonator filters are connected. Also, in FIG.
1 shows a resonator filter with a stage configuration. In FIG. 9, pad 1 is connected to an input signal terminal, and pads 2 and 3 are grounded on the input side (hereinafter, abbreviated as GND). When an electric signal is input to the IDT 12 through the pads 1 and 3, surface acoustic waves are generated on the piezoelectric substrate, which are IDT11 and IDT1.
It is received by 3 and converted into an electric signal again. This electric signal becomes a surface acoustic wave again by the IDT 11a and IDT 13a, is finally received by the IDT 12a and converted into an electric signal, and is output to the output signal terminal via the pad 6. Pads 4 and 5 are connected to output side GND, and input / output GND
Are connected to each other and have a common potential. IDT
11, reflectors 7 and 8 on the outside of the IDT 13
Reflectors 7a and 8a are provided outside the a and IDT 13a, respectively. The frequency characteristics obtained with this configuration are shown in FIG. Further, FIG. 12 shows frequency characteristics obtained by the one-stage resonator filter shown in FIG.

【0005】[0005]

【発明が解決しようとする課題】しかしながら、この 1
段構成の共振子型フイルタは、低損失ではあるが帯域外
減衰量が不十分であり、また帯域外減衰量を確保するた
め多段にすると帯域内での損失が悪化するという問題が
あった。
[Problems to be Solved by the Invention] However, this 1
The resonator type filter having a multi-stage structure has a problem that the out-of-band attenuation amount is insufficient although the loss is low, and the loss in the band is deteriorated when the number of stages is increased to secure the out-band attenuation amount.

【0006】また、 LADDER 型フイルタにおいては帯域
内での低損失は得られるものの帯域外については、直列
共振子の反共振点、並列共振子の共振点では高い減衰量
が得られるが、より広い周波数範囲では減衰量が不十分
となる傾向がみられるという問題があった。
Further, in the LADDER type filter, although low loss is obtained within the band, high attenuation is obtained at the anti-resonance point of the series resonator and the resonance point of the parallel resonator outside the band, but wider. There is a problem that the attenuation tends to be insufficient in the frequency range.

【0007】本発明はこのような課題に対処するために
なされたもので、 3IDT 共振子型構造をベースに充分な
帯域幅と帯域外減衰量を両立させた弾性波表面波フィル
タ、とくに自動車電話などの移動体通信用弾性表面波フ
ィルタ装置を提供することを目的とする。
The present invention has been made to address such a problem, and is based on a 3IDT resonator type structure, and has a surface acoustic wave filter which has both a sufficient bandwidth and an out-of-band attenuation amount, particularly a mobile phone. It is an object of the present invention to provide a surface acoustic wave filter device for mobile communication such as.

【0008】[0008]

【課題を解決するための手段】本発明の弾性表面波フィ
ルタ装置は、圧電性基板上に形成された 3個の IDTとそ
の両側に形成された反射器とを備え、 IDTの入出力の少
なくとも 1方に、少なくとも 1つ以上の共振子よりなる
ノッチフィルタを直列および並列に付加したことを特徴
とする。
A surface acoustic wave filter device of the present invention comprises three IDTs formed on a piezoelectric substrate and reflectors formed on both sides thereof, and at least the input / output of the IDT. One side is characterized by adding a notch filter consisting of at least one resonator in series and in parallel.

【0009】また、直列に付加されるノッチフィルタの
反共振周波数は IDTの通過帯域内よりも高域側に、前記
並列に付加されたノッチフィルタの共振周波数は IDTの
通過帯域内よりも低域側に設定されていることを特徴と
する。
The anti-resonance frequency of the notch filters added in series is higher than the pass band of the IDT, and the resonance frequency of the notch filters added in parallel is lower than the pass band of the IDT. It is characterized by being set to the side.

【0010】本発明に係わるノッチフィルタはそれが接
続された 3個の IDTと同一の圧電性基板上に形成されて
いることが好ましく、また、ノッチフィルタの構成は 1
個のIDTおよびそれをはさむ 1対の反射器よりなる弾性
表面波共振子、または 1個のIDTのみからなる弾性表面
波共振子であることが好ましい。
The notch filter according to the present invention is preferably formed on the same piezoelectric substrate as the three IDTs to which the notch filter is connected.
A surface acoustic wave resonator including one IDT and a pair of reflectors sandwiching the IDT, or a surface acoustic wave resonator including only one IDT is preferable.

【0011】本発明の弾性表面波フィルタ装置が主に使
用されるコードレス電話や携帯電話における RF フイル
タの帯域は 1%から 5%である。これを実現する上にお
いて本発明に係わる圧電性基板は、 2%以上の電気機械
結合係数を有することが好ましい。具体的には36゜Y-X
タンタル酸リチウム、64゜Y-X ニオブ酸リチウム、41゜
Y-X ニオブ酸リチウム等を挙げることができる。
The band of the RF filter in a cordless telephone or a mobile telephone in which the surface acoustic wave filter device of the present invention is mainly used is 1% to 5%. To realize this, the piezoelectric substrate according to the present invention preferably has an electromechanical coupling coefficient of 2% or more. Specifically, 36 ° YX
Lithium tantalate, 64 ° YX Lithium niobate, 41 °
Examples include YX lithium niobate and the like.

【0012】[0012]

【作用】くし形変換器の入出力の少なくとも 1方に、少
なくとも 1つ以上の共振子よりなるノッチフィルタを直
列および並列に付加すると、充分な帯域幅と帯域外減衰
量を両立させることができる。すなわち 3IDT の段数を
極力減らし、帯域幅を確保し、引換えに劣化した帯域外
特性をノッチフィルタで補うことにより充分な帯域外減
衰量を得ることができる。
By adding a notch filter consisting of at least one resonator in series and in parallel to at least one of the input and output of the comb converter, it is possible to achieve both sufficient bandwidth and out-of-band attenuation. . That is, a sufficient out-of-band attenuation can be obtained by reducing the number of stages of 3IDT as much as possible, securing a bandwidth, and compensating for the deteriorated out-of-band characteristic in exchange.

【0013】[0013]

【実施例】図1(a)は本実施例に係わる電極パターン
図である。また、図1(b)は 3IDT およびノッチフィ
ルタの接続状態を示す概念図である。両側に反射器 Gr
7、 Gr 8を有して IDT11、 IDT12、 IDT13が横
一列に、64゜Y-X ニオブ酸リチウム( LiNbO3 )基板上
に配設される。パッド1から入力された電気信号は接続
された直並列共振子を通り IDT11および IDT13に伝
えられ、これらにより励起された弾性表面波は中央の I
DT12で受けられる。その際漏洩した表面波も両側の反
射器 Gr 7および Gr 8で反射され再度 IDT側へ返され
るため、この電極構造は基本的に低損失フイルタに適し
ている。ここで中央の IDT12はパッド6が出力端子、
他のパッド2、パッド3、パッド4は GNDに接続され
る。
EXAMPLE FIG. 1A is an electrode pattern diagram according to this example. Also, FIG. 1B is a conceptual diagram showing a connection state of the 3IDT and the notch filter. Reflectors on both sides Gr
7, IDT 11, IDT 12, and IDT 13 having Gr 8 are arranged in a row in a row on a 64 ° YX lithium niobate (LiNbO 3 ) substrate. The electric signal input from the pad 1 is transmitted to the IDT 11 and IDT 13 through the connected series-parallel resonator, and the surface acoustic wave excited by these is I
Received at DT12. At that time, the leaked surface wave is also reflected by the reflectors Gr 7 and Gr 8 on both sides and returned to the IDT side again, so this electrode structure is basically suitable for a low loss filter. Here, in the center IDT 12, the pad 6 is the output terminal,
The other pads 2, 3, and 4 are connected to GND.

【0014】パッド1には、共振子(I) および共振子(I
I)が直列に、さらに共振子(III) が並列に、それぞれ接
続されている。ここで共振子(I) は、反射器 Gr 9、 G
r 10とそれによって挟まれた IDT14より、共振子(I
I)は、反射器 Gr 9a、 Gr10aとそれによって挟ま
れた IDT15より、共振子(III) は、反射器 Gr 9b、
Gr 10bとそれによって挟まれた IDT16より構成さ
れている。この直列および並列接続の共振子がノッチフ
ィルタとして働いている。図1(b)にそのノッチフィ
ルタの接続状態をブロック図的に示す。
The pad 1 has a resonator (I) and a resonator (I).
I) is connected in series, and the resonator (III) is connected in parallel. Here, the resonator (I) is a reflector Gr 9, G
From the r 10 and the IDT 14 sandwiched by it, the resonator (I
I) is based on the reflectors Gr 9a and Gr 10a and the IDT 15 sandwiched by them, and the resonator (III) is based on the reflectors Gr 9b and
It consists of Gr 10b and IDT 16 sandwiched by it. The series and parallel connected resonators function as a notch filter. FIG. 1B is a block diagram showing the connection state of the notch filter.

【0015】本実施例に係わる弾性表面波フィルタ装置
の周波数特性に関するシュミレーションを行った。その
結果を図2〜図6に示す。図2は共振子(I) 、共振子(I
I)および共振子(III) が接続されていないとした場合
を、図3は共振子(I) のみの場合を、図4は共振子(II)
のみの場合を、図5は共振子(III) のみの場合を、図6
は本実施例の場合をそれぞれ示す。図2は従来の弾性表
面波フィルタ装置のシュミレーション結果でもある。
A simulation of frequency characteristics of the surface acoustic wave filter device according to this example was carried out. The results are shown in FIGS. Figure 2 shows the resonator (I) and the resonator (I
I) and the resonator (III) are not connected, Fig. 3 shows only the resonator (I), and Fig. 4 shows the resonator (II).
6 shows the case of only the resonator (III), and FIG.
Shows the case of this embodiment, respectively. FIG. 2 also shows a simulation result of a conventional surface acoustic wave filter device.

【0016】本実施例は 3IDT でシステム帯域を作成
し、低域側の減衰量を並列配置の共振子(III) の共振点
で、高域側の減衰量を 2つの直列配置の共振子(I) およ
び共振子(II)の反共振点で確保するように周波数設定し
た。図6に示すように、本実施例のシュミレーション結
果は、従来の 3IDT 単体の場合に比較して共振子の共振
もしくは反共振点に相当する周波数で明らかに減衰量は
増加している。
In this embodiment, a system band is created by 3IDT, and the attenuation amount on the low frequency side is the resonance point of the resonator (III) arranged in parallel, and the attenuation amount on the high frequency side is two resonators arranged in series ( The frequency was set so as to ensure at the anti-resonance point of I) and the resonator (II). As shown in FIG. 6, in the simulation result of this embodiment, the amount of attenuation is obviously increased at the frequency corresponding to the resonance or antiresonance point of the resonator, as compared with the case of the conventional 3IDT alone.

【0017】本実施例で得られた弾性表面波フィルタ装
置の周波数特性の実測値を図7および図8に示す。図7
に示すように、帯域での挿入損失は 3dBにとどまりなが
らも、帯域外減衰量は 20 dBを確保している。また図8
に示すように、この帯域外減衰量は広い周波数帯にわた
って維持されている。その結果、本実施例で得られた弾
性表面波フィルタ装置は十分実用に耐え得ることができ
る。
The measured values of the frequency characteristics of the surface acoustic wave filter device obtained in this embodiment are shown in FIGS. 7 and 8. Figure 7
As shown in, while the insertion loss in the band is only 3 dB, the out-of-band attenuation is 20 dB. See also FIG.
As shown in, the out-of-band attenuation is maintained over a wide frequency band. As a result, the surface acoustic wave filter device obtained in this example can be sufficiently put to practical use.

【0018】なお、 3IDT やこれに直列および並列に付
加したノッチフィルタの数は、目的とするフィルタ特性
によって任意に選択することができる。また、ノッチフ
ィルタの配列も入力側、出力側に任意に選択することが
できる。さらに基板として36゜Y-X タンタル酸リチウム
( LiTaO3 )を用いても本実施例と同様な効果を得るこ
とができる。
The 3IDT and the number of notch filters added in series and in parallel to the 3IDT can be arbitrarily selected according to the desired filter characteristics. Further, the array of notch filters can be arbitrarily selected on the input side and the output side. Further, even if 36 ° YX lithium tantalate (LiTaO 3 ) is used as the substrate, the same effect as this embodiment can be obtained.

【0019】[0019]

【発明の効果】本発明の弾性表面波フィルタ装置は、圧
電性基板上に 3個の IDTとその両側に反射器を備えた、
IDTの入出力の少なくとも 1方に、少なくとも 1つ以上
の共振子よりなるノッチフィルタを直列および並列に付
加したので、広帯域で低損失かつ帯域外減衰量を大きく
とることができ、充分な帯域幅と帯域外減衰量を両立さ
せることができる。
The surface acoustic wave filter device of the present invention comprises three IDTs on the piezoelectric substrate and reflectors on both sides thereof.
Since a notch filter consisting of at least one resonator is added in series and in parallel to at least one of the input and output of the IDT, wide band low loss and large out-of-band attenuation can be achieved, and a sufficient bandwidth is obtained. And out-of-band attenuation can be compatible.

【図面の簡単な説明】[Brief description of drawings]

【図1】実施例1に係わる弾性表面波フィルタ装置の電
極パターン図である。
FIG. 1 is an electrode pattern diagram of a surface acoustic wave filter device according to a first embodiment.

【図2】共振子(I) 、(II)および(III) が接続されてい
ない場合の周波数特性を示す図である。
FIG. 2 is a diagram showing frequency characteristics when resonators (I), (II) and (III) are not connected.

【図3】共振子(I) のみの場合の周波数特性シュミレー
ション結果を示す図である。
FIG. 3 is a diagram showing a frequency characteristic simulation result in the case of only a resonator (I).

【図4】共振子(II)のみの場合の周波数特性シュミレー
ション結果を示す図である。
FIG. 4 is a diagram showing a frequency characteristic simulation result when only a resonator (II) is used.

【図5】共振子(III) のみの場合の周波数特性シュミレ
ーション結果を示す図である。
FIG. 5 is a diagram showing a frequency characteristic simulation result in the case of only the resonator (III).

【図6】本実施例の場合の周波数特性を示す図である。FIG. 6 is a diagram showing frequency characteristics in the case of the present embodiment.

【図7】本実施例の場合の周波数特性の実測値を示す図
である。
FIG. 7 is a diagram showing measured values of frequency characteristics in the case of the present embodiment.

【図8】本実施例の場合の広域周波数特性の実測値を示
す図である。
FIG. 8 is a diagram showing actual measured values of wide-range frequency characteristics in the case of the present embodiment.

【図9】従来の 2段構成の共振子型フィルタ装置の電極
パターン図である。
FIG. 9 is an electrode pattern diagram of a conventional resonator filter device having a two-stage configuration.

【図10】従来の 2段構成の共振子型フィルタ装置の周
波数特性を示す図である。
FIG. 10 is a diagram showing frequency characteristics of a conventional two-stage resonator type filter device.

【図11】従来の 1段構成の共振子型フィルタ装置の電
極パターン図である。
FIG. 11 is an electrode pattern diagram of a conventional one-stage resonator type filter device.

【図12】従来の 1段構成の共振子型フィルタ装置の周
波数特性を示す図である。
FIG. 12 is a diagram showing frequency characteristics of a conventional one-stage resonator type filter device.

【符号の説明】 1〜6………パッド、7〜10………反射器、11〜1
6……… IDT。
[Explanation of Codes] 1 to 6 ... Pads, 7 to 10 ... Reflectors, 11 to 1
6 ... IDT.

Claims (2)

【特許請求の範囲】[Claims] 【請求項1】 圧電性基板上に形成された 3個のくし形
変換器とその両側に形成された反射器とを備えた弾性表
面波フィルタ装置において、 前記くし形変換器の入出力の少なくとも 1方に、少なく
とも 1つ以上の共振子よりなるノッチフィルタを直列お
よび並列に付加したことを特徴とする弾性表面波フィル
タ装置。
1. A surface acoustic wave filter device including three comb-shaped transducers formed on a piezoelectric substrate and reflectors formed on both sides of the comb-shaped transducers. A surface acoustic wave filter device, wherein a notch filter including at least one resonator is added in series and in parallel to one side.
【請求項2】 請求項1記載の弾性表面波フィルタ装置
において、前記直列に付加されたノッチフィルタの反共
振周波数は前記くし形変換器の通過帯域内よりも高域側
に、前記並列に付加されたノッチフィルタの共振周波数
は前記くし形変換器の通過帯域内よりも低域側に設定さ
れていることを特徴とする弾性表面波フィルタ装置。
2. The surface acoustic wave filter device according to claim 1, wherein the anti-resonance frequency of the notch filter added in series is added in parallel to the higher band side than the pass band of the comb converter. The resonance frequency of the notch filter is set to a lower frequency side than a pass band of the comb-shaped converter.
JP19545494A 1994-08-19 1994-08-19 Surface acoustic wave filter device Withdrawn JPH0865097A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP19545494A JPH0865097A (en) 1994-08-19 1994-08-19 Surface acoustic wave filter device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP19545494A JPH0865097A (en) 1994-08-19 1994-08-19 Surface acoustic wave filter device

Publications (1)

Publication Number Publication Date
JPH0865097A true JPH0865097A (en) 1996-03-08

Family

ID=16341340

Family Applications (1)

Application Number Title Priority Date Filing Date
JP19545494A Withdrawn JPH0865097A (en) 1994-08-19 1994-08-19 Surface acoustic wave filter device

Country Status (1)

Country Link
JP (1) JPH0865097A (en)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0998039A1 (en) * 1997-07-18 2000-05-03 Kabushiki Kaisha Toshiba Surface acoustic wave filter
US6201457B1 (en) * 1998-11-18 2001-03-13 Cts Corporation Notch filter incorporating saw devices and a delay line
US6366179B1 (en) 1998-08-06 2002-04-02 Kabushiki Kaisha Toshiba Surface acoustic wave element having two filters with more IDTs in the lower frequency filter
US6710677B2 (en) * 2002-02-12 2004-03-23 Nortel Networks Limited Band reject filters
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
US6924715B2 (en) * 2002-02-12 2005-08-02 Nortel Networks Limited Band reject filters
US8125300B2 (en) * 2007-02-19 2012-02-28 Epcos Ag Surface acoustic wave filter comprising a band-pass filter and a band-stop filter
US8269577B2 (en) 2008-10-31 2012-09-18 Taiyo Yuden Co., Ltd. Acoustic wave filter, duplexer, communication module, and communication apparatus
US20120306595A1 (en) * 2010-03-01 2012-12-06 Murata Manufacturing Co., Ltd. Elastic-wave filter device

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0998039A1 (en) * 1997-07-18 2000-05-03 Kabushiki Kaisha Toshiba Surface acoustic wave filter
EP0998039B1 (en) * 1997-07-18 2016-12-28 Murata Manufacturing Co., Ltd. Surface acoustic wave filter
US6366179B1 (en) 1998-08-06 2002-04-02 Kabushiki Kaisha Toshiba Surface acoustic wave element having two filters with more IDTs in the lower frequency filter
US6201457B1 (en) * 1998-11-18 2001-03-13 Cts Corporation Notch filter incorporating saw devices and a delay line
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
US6710677B2 (en) * 2002-02-12 2004-03-23 Nortel Networks Limited Band reject filters
US6924715B2 (en) * 2002-02-12 2005-08-02 Nortel Networks Limited Band reject filters
US8125300B2 (en) * 2007-02-19 2012-02-28 Epcos Ag Surface acoustic wave filter comprising a band-pass filter and a band-stop filter
US8269577B2 (en) 2008-10-31 2012-09-18 Taiyo Yuden Co., Ltd. Acoustic wave filter, duplexer, communication module, and communication apparatus
US20120306595A1 (en) * 2010-03-01 2012-12-06 Murata Manufacturing Co., Ltd. Elastic-wave filter device
US8410869B2 (en) * 2010-03-01 2013-04-02 Murata Manufacturing Co., Ltd. Elastic-wave filter device having a band-pass filter and a band-reject filter

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