JPH10294644A - Polar surface acoustic wave device - Google Patents
Polar surface acoustic wave deviceInfo
- Publication number
- JPH10294644A JPH10294644A JP11618097A JP11618097A JPH10294644A JP H10294644 A JPH10294644 A JP H10294644A JP 11618097 A JP11618097 A JP 11618097A JP 11618097 A JP11618097 A JP 11618097A JP H10294644 A JPH10294644 A JP H10294644A
- Authority
- JP
- Japan
- Prior art keywords
- filter
- mode
- resonance
- saw filter
- 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.)
- Pending
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Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は弾性表面波フィルタ
に関し、特に複数の縦結合多重モードフィルタを並列接
続して構成した共振合成型表面波フィルタにおいて、通
過帯域近傍に減衰極を設けることにより減衰傾度を急峻
にした共振合成型表面波フィルタに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave filter, and more particularly to a surface acoustic wave filter comprising a plurality of longitudinally coupled multimode filters connected in parallel to each other by providing an attenuation pole near a pass band. The present invention relates to a resonance type surface acoustic wave filter having a steep gradient.
【0002】[0002]
【従来の技術】近年、弾性表面波フィルタ(以下、SA
Wフィルタと称す)は小型化、高周波化、量産性等に優
れているため、携帯電話をはじめとする無線機のRF及
びIF段のフィルタとして多く利用されている。特に最
近のGSM、CDMA等のデジタル通信方式の無線機の
第一IFフィルタ用には広帯域フィルタの条件に加え、
より急峻なカットオフ特性が要求され、隣接チャンネル
の信号を分離する高選択性を有することが重要な要素と
なっている。2. Description of the Related Art Recently, a surface acoustic wave filter (hereinafter referred to as SA) has been developed.
W filters) are excellent in miniaturization, higher frequency, mass productivity, and the like, and are therefore often used as RF and IF stage filters for wireless devices such as mobile phones. In particular, in addition to the conditions of the wideband filter, the first IF filter of a digital communication radio such as recent GSM and CDMA is used.
A sharper cutoff characteristic is required, and it is an important factor to have high selectivity for separating signals of adjacent channels.
【0003】図16(a)は従来の共振合成型SAWフ
ィルタの模式的電極パターンを示す平面図であって、圧
電基板20の主面上に表面波の伝搬方向に沿って2個の
IDT21a、21cとその間にグレーティング21b
を配し、IDT両側に反射器22a、22bを配置し、
音響結合の結果生ずる3個のモードを利用して縦結合三
重モードフィルタA(フィルタA)を構成する。周知の
ように、音響結合の結果生ずる3個の縦モードを低次モ
ードからA1(1次)、A2(2次)及びA3(3次)
とし、その共振周波数をそれぞれFa1、Fa2及びF
a3とすると、縦結合多重モードフィルタにおいては高
次モードになるにつれその共振周波数は低周波側に生じ
る。即ち、Fa3<Fa2<Fa1の周波数関係にな
る。前記縦結合三重モードフィルタAと同様に、圧電基
板20上に表面波の伝搬方向に沿って3個のIDT23
a、23b、23cとその両側に反射器24a、24b
を配置して、音響結合の結果生ずる3個のモードを利用
して縦結合三重モードフィルタB(フィルタB)を構成
する。該フィルタBの3個のモードを低次からB1(1
次)、B2(2次)及びB3(3次)とし、その共振周
波数をFb1、Fb2及びFb3とすると、Fb3<F
b2<Fb1となる。FIG. 16A is a plan view showing a schematic electrode pattern of a conventional resonance-combination type SAW filter. Two IDTs 21a are arranged on a main surface of a piezoelectric substrate 20 along a propagation direction of a surface wave. 21c and grating 21b between them
And reflectors 22a and 22b are arranged on both sides of the IDT,
A longitudinally-coupled triple-mode filter A (filter A) is constructed using three modes generated as a result of acoustic coupling. As is well known, the three longitudinal modes resulting from acoustic coupling are changed from low order modes to A1 (first order), A2 (secondary) and A3 (third order).
And their resonance frequencies are Fa1, Fa2 and F2, respectively.
Assuming that a3 is used, in the longitudinally coupled multimode filter, the higher the higher-order mode, the higher its resonance frequency is generated on the lower frequency side. That is, the frequency relationship of Fa3 <Fa2 <Fa1 is satisfied. Similarly to the longitudinally coupled triple mode filter A, three IDTs 23 are arranged on the piezoelectric substrate 20 along the propagation direction of the surface wave.
a, 23b, 23c and reflectors 24a, 24b on both sides thereof
Are arranged, and a longitudinally coupled triple mode filter B (filter B) is configured using three modes resulting from acoustic coupling. The three modes of the filter B are changed from low order to B1 (1
Next, B2 (secondary) and B3 (third), and their resonance frequencies are Fb1, Fb2 and Fb3, Fb3 <F
b2 <Fb1.
【0004】上記フィルタAとBとの対応するモード同
士、例えば前記モードA1とB1との位相が互いに逆相
になるように、フィルタAのIDT電極指に対しフィル
タBの電極指を極性に配慮して配置する。更に、前記フ
ィルタAとBの共振周波数の配列関係をFa2=Fb
3、Fa1=Fb2となるように上記IDT電極指の周
期を設定し、フィルタAとBとを電気的に並列接続して
構成したものが所謂共振合成型SAWフィルタCであ
る。図16(b)は共振点を明らかにすべくフィルタA
の終端インピーダンスをミスマッチさせたときの伝送特
性を示したものであり、縦軸に損失(Loss)、横軸
に周波数をとると、縦モードのA1(1次)、A2(2
次)及びA3(3次)モードの共振周波数に相当する3
個の共振ピークFa1、Fa2及びFa3が顕著に現れ
る。上記モードの位相関係は、A1(1次)モードの位
相を0度とすると、A2(2次)モードは180度、A
3(3次)モードは0度となり、縦軸に位相(Phas
e)、横軸に周波数を取ると図15(b)に示すように
なる。The electrode fingers of the filter B are considered with respect to the IDT electrode fingers of the filter A so that the corresponding modes of the filters A and B, for example, the modes A1 and B1 have opposite phases. And place it. Further, the arrangement relationship between the resonance frequencies of the filters A and B is expressed as Fa2 = Fb
3. A so-called resonance combined type SAW filter C is configured by setting the period of the IDT electrode finger so that Fa1 = Fb2 and electrically connecting filters A and B in parallel. FIG. 16B shows a filter A for clarifying the resonance point.
And the transmission characteristics when the terminal impedances are mismatched. When the vertical axis represents loss (Loss) and the horizontal axis represents frequency, A1 (primary) and A2 (2
3) corresponding to the resonance frequencies of the (next) and A3 (third) modes.
Resonance peaks Fa1, Fa2, and Fa3 appear remarkably. The phase relationship between the above modes is as follows: if the phase of the A1 (primary) mode is 0 degree, the phase of the A2 (secondary) mode is 180 degrees;
The third (third-order) mode is 0 degree, and the vertical axis indicates the phase (Phas).
e), the frequency is plotted on the horizontal axis, as shown in FIG.
【0005】図16(c)は図16(a)に示すフィル
タBの終端インピーダンスをミスマッチさせたときの伝
送特性を示したものであり、同(b)と同様に縦モード
のB1(1次)、B2(2次)、B3(3次)モードの
共振周波数に相当する3個の共振ピークFb1、Fb2
及びFb3が顕著に現れる。これらのモードの位相は、
フィルタAの対応するモードの位相と逆相になるように
フィルタBのIDTの極性を考慮して配置しているた
め、B1(1次)モードの位相は180度となり、B2
(2次)は0度、B3(3次)は180度の位相とな
る。図16(d)は、図16(a)に示すようにフィル
タAとBとを電気的に並列接続して構成した共振合成型
SAWフィルタCの終端インピーダンスをミスマッチさ
せた場合の伝送特性を示したものであり、4つの共振ピ
ークを有する。該フィルタに適切な終端を施し、インピ
ーダンスのマッチングをとることにより図17に示すよ
うな4次のフィルタの濾波特性αを得ることができる。
同図の曲線βは共振合成型SAWフィルタCの群遅延時
間特性である。FIG. 16 (c) shows transmission characteristics when the terminal impedance of the filter B shown in FIG. 16 (a) is mismatched. As in FIG. ), Three resonance peaks Fb1 and Fb2 corresponding to the resonance frequencies of the B2 (secondary) and B3 (third) modes.
And Fb3 appear remarkably. The phase of these modes is
Since the filter B is arranged in consideration of the polarity of the IDT of the filter B so as to have a phase opposite to that of the corresponding mode of the filter A, the phase of the B1 (primary) mode is 180 degrees, and
(Second order) has a phase of 0 degrees, and B3 (third order) has a phase of 180 degrees. FIG. 16D shows transmission characteristics when the terminal impedance of the resonance combined type SAW filter C configured by electrically connecting the filters A and B electrically as shown in FIG. 16A is mismatched. And has four resonance peaks. By appropriately terminating the filter and matching the impedance, a filtering characteristic α of a fourth-order filter as shown in FIG. 17 can be obtained.
A curve β in the figure is a group delay time characteristic of the resonance combined type SAW filter C.
【0006】[0006]
【発明が解決しようとする課題】しかしながら上記の従
来の共振合成型SAWフィルタおいては、カットオフ近
傍の減衰傾度が、例えばデジタル通信方式の第1IF用
の要求に比べて不十分であるという問題がある。また、
要求を満たすべく同種のフィルタを縦続接続すれば減衰
傾度は改善されるが、該フィルタの挿入損失が増大し無
線機の受信性能を劣化させるという問題がある。一方、
IDTの両側に反射器を配置して形成するSAW共振子
を梯子型状に接続して構成する梯子型SAWフィルタ
(ラダー型SAWフィルタ)は、有極構成が可能となる
ので急峻な減衰傾度を有するSAWフィルタが実現でき
る。この理由で最近、各種の無線機に用いられている
が、ラチス型回路のSAWフィルタに比べ狭帯域となる
ため、ディジタル通信方式のように広帯域のフィルタを
要求する方式に適さないという問題がある。本発明は上
記問題を解決するためになされたものであって、カット
オフ近傍の減衰傾度を改善し、挿入損失の小さな共振合
成型SAWフィルタを提供することを目的とする。However, in the above-mentioned conventional resonance-combined SAW filter, the problem is that the attenuation gradient near the cutoff is insufficient, for example, as required for the first IF of the digital communication system. There is. Also,
If the same type of filter is cascaded to satisfy the requirement, the attenuation gradient can be improved, but there is a problem that the insertion loss of the filter increases and the receiving performance of the radio device deteriorates. on the other hand,
A ladder-type SAW filter (ladder-type SAW filter) configured by connecting a SAW resonator formed by arranging reflectors on both sides of an IDT in a ladder-type configuration has a steep attenuation gradient because a polarized configuration is possible. A SAW filter can be realized. For this reason, recently, it is used for various wireless devices, but has a problem that it is not suitable for a system requiring a wide band filter such as a digital communication system because it has a narrower band than a SAW filter of a lattice type circuit. . SUMMARY OF THE INVENTION The present invention has been made to solve the above problem, and an object of the present invention is to provide a resonance combined type SAW filter having an improved attenuation gradient near a cutoff and a small insertion loss.
【0007】[0007]
【課題を解決するための手段】上記目的を達成するため
に本発明に係る有極型表面波フィルタの請求項1記載の
発明は、圧電基板上に少なくとも2個のIDTとその最
外側に反射器を配置し励起される表面波の音響結合を利
用して構成した結合型多重モードSAWフィルタを少な
くとも2個併置し電気的に並列接続して構成した共振合
成型SAWフィルタにおいて、前記結合型多重モードS
AWフィルタの一方の多重モードSAWフィルタが有す
る振動モードの少なくとも1と、他方の多重モードSA
Wフィルタが有する振動モードの少なくとも1とが、互
いに共振周波数が等しく、且つ該共振周波数での互いの
入出力間位相シフト量が(2n+1)π(n=0,1,
2・・)異なることを特徴とする有極型弾性表面波フィ
ルタである。請求項2記載の発明は、前記多重モードS
AWフィルタが縦結合多重モードSAWフィルタである
ことを特徴とする請求項1記載の有極型弾性表面波フィ
ルタである。請求項3記載の発明は、前記多重モードS
AWフィルタが圧電基板上に表面波の伝搬方向に沿って
入出力IDTとその両側に反射器を配置し該入出力ID
T間にグレーティングを配して構成した縦結合多重モー
ドSAWフィルタであることを特徴とする請求項1記載
の有極型弾性表面波フィルタである。請求項4記載の発
明は前記多重モードSAWフィルタが横結合多重モード
SAWフィルタであることを特徴とする請求項1記載の
有極型弾性表面波フィルタである。請求項5記載の発明
は前記多重モードSAWフィルタが表面波の伝搬方向の
結合を利用した縦モード共振と、伝搬方向に垂直な横モ
ード共振とを結合させた二次元モード結合多重モードS
AWフィルタであることを特徴とする請求項1記載の有
極型弾性表面波フィルタである。請求項6記載の発明は
前記多重モードSAW共振器フィルタの一方が縦結合多
重モードSAWフィルタであり、他方が横結合多重モー
ドSAWフィルタであることを特徴とする請求項1記載
の有極型弾性表面波フィルタである。請求項7記載の発
明は前記多重モードSAWフィルタの一方が縦結合多重
モードSAWフィルタであり、他方が二次元モード結合
多重モードSAWフィルタであることを特徴とする請求
項1記載の有極型弾性表面波フィルタである。請求項8
記載の発明は前記多重モードSAWフィルタの一方が横
結合多重モードSAWフィルタであり、他方が二次元モ
ード結合多重モードSAWフィルタであることを特徴と
する請求項1記載の有極型弾性表面波フィルタである。
請求項9記載の発明は請求項1から請求項8に記載の有
極型弾性表面波フィルタを少なくとも1つ用いて縦続構
成したことを特徴とする有極型弾性表面波フィルタであ
る。According to a first aspect of the present invention, there is provided a polarized type surface acoustic wave filter according to the present invention, wherein at least two IDTs are reflected on a piezoelectric substrate and reflected outwardly. A resonant combined SAW filter comprising at least two coupled multi-mode SAW filters, each of which is configured by utilizing an acoustic coupling of a surface wave to be excited and disposed, and electrically connected in parallel. Mode S
At least one of the vibration modes of one multi-mode SAW filter of the AW filter and the other multi-mode SA
At least one of the vibration modes of the W filter has the same resonance frequency, and the phase shift between the input and the output at the resonance frequency is (2n + 1) π (n = 0, 1,
2) A polarized surface acoustic wave filter characterized by being different. The invention according to claim 2 is characterized in that the multi-mode S
2. The polarized surface acoustic wave filter according to claim 1, wherein the AW filter is a longitudinally coupled multi-mode SAW filter. The invention according to claim 3 is characterized in that the multi-mode S
An AW filter arranges an input / output IDT on a piezoelectric substrate along a propagation direction of a surface acoustic wave and reflectors on both sides thereof.
2. The polarized surface acoustic wave filter according to claim 1, wherein the filter is a longitudinally coupled multi-mode SAW filter having a grating disposed between T. The invention according to claim 4 is the polarized surface acoustic wave filter according to claim 1, wherein the multi-mode SAW filter is a transversely coupled multi-mode SAW filter. According to a fifth aspect of the present invention, there is provided a two-dimensional mode coupled multimode S in which the multimode SAW filter couples longitudinal mode resonance utilizing coupling in the propagation direction of a surface wave and transverse mode resonance perpendicular to the propagation direction.
2. The polarized surface acoustic wave filter according to claim 1, which is an AW filter. The invention according to claim 6 is characterized in that one of the multimode SAW resonator filters is a longitudinally coupled multimode SAW filter and the other is a transversely coupled multimode SAW filter. This is a surface acoustic wave filter. The invention according to claim 7, wherein one of the multimode SAW filters is a longitudinally coupled multimode SAW filter and the other is a two-dimensional mode coupled multimode SAW filter. This is a surface acoustic wave filter. Claim 8
2. The polarized surface acoustic wave filter according to claim 1, wherein one of the multi-mode SAW filters is a transversely coupled multi-mode SAW filter and the other is a two-dimensional mode-coupled multi-mode SAW filter. It is.
According to a ninth aspect of the present invention, there is provided a polarized surface acoustic wave filter comprising at least one polar surface acoustic wave filter according to any one of the first to eighth aspects.
【0008】[0008]
【発明の実施の形態】以下本発明を図面に示した実施の
形態に基づいて詳細に説明する。図1(a)は本発明に
係る共振合成型SAWフィルタの第1の実施例を示す模
式的平面図である。始めに、圧電基板1の主面上に表面
波の伝搬方向に沿って2個のIDT2a、2cとその間
にグレーティング2bを配し、IDTの両側に反射器3
a、3bを配置して縦結合三重モードSAWフィルタ
(フィルタA)を構成する。該フィルタAにおいては縦
モード間の音響結合のより3個のモードA1(1次)、
A2(2次)及びA3(3次)が強勢に励振され、その
共振周波数をそれぞれFa1、Fa2及びFa3とする
と、縦結合モードの場合の周波数関係はFa3<Fa2
<Fa1となる。次に、フィルタAと同様に、圧電基板
1上に表面波の伝搬方向に沿って2個のIDT4a、4
cとその間にグレーティング4bを配し、IDTの両側
に反射器5a、5bを配置して構成した縦結合三重モー
ドSAWフィルタをフィルタBとする。フィルタAと同
様に、音響結合により3個のモードB1(1次)、B2
(2次)及びB3(3次)が強勢に励振され、その共振
周波数をそれぞれFb1、Fb2及びFb3とすると、
Fa3<Fa2<Fa1の周波数配列になる。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on an embodiment shown in the drawings. FIG. 1A is a schematic plan view showing a first embodiment of a resonance-combined SAW filter according to the present invention. First, two IDTs 2a, 2c and a grating 2b are arranged on the main surface of the piezoelectric substrate 1 along the propagation direction of the surface wave, and reflectors 3 are provided on both sides of the IDT.
a, 3b are arranged to constitute a longitudinally coupled triple mode SAW filter (filter A). In the filter A, three modes A1 (first order) of acoustic coupling between longitudinal modes,
If A2 (secondary) and A3 (third order) are strongly excited and their resonance frequencies are Fa1, Fa2 and Fa3, respectively, the frequency relationship in the longitudinal coupling mode is Fa3 <Fa2.
<Fa1. Next, similarly to the filter A, the two IDTs 4a, 4
The filter B is a longitudinally coupled triple mode SAW filter configured by arranging a grating 4b and the reflectors 5a and 5b on both sides of the IDT. Similarly to the filter A, three modes B1 (primary) and B2
(Second order) and B3 (third order) are strongly excited, and their resonance frequencies are Fb1, Fb2, and Fb3, respectively.
The frequency array becomes Fa3 <Fa2 <Fa1.
【0009】図1(a)に示すように、フィルタBは、
フィルタAと逆位相になるように2個のIDTうち1個
のIDT(図1(a)では入力側)の電極指をλ/2だ
けずらして配置してある。フィルタAとフィルタBを電
気的に並列接続して所謂共振合成型SAWフィルタCを
構成している。図1(b)はフィルタAの終端インピー
ダンスをミスマッチさせた場合の伝送特性と位相特性で
あり、図1(c)はフィルタBの終端インピーダンスを
ミスマッチさせた場合の伝送特性と位相特性である。
尚、結合型多重モード表面波共振子の各共振点の周波数
を可変するためには、IDTの対数を可変する方法、入
力と出力のIDTを規則的に配列されている周期からず
らす方法、電極の膜厚を可変する方法等の周知の手法を
適宜組み合わせて行えばよい。ここで図1(b)、
(c)に示すようにフィルタAとBの共振周波数の関係
をFa1=Fb1、Fa3=Fb2の周波数関係をほぼ
満たすようにフィルタAとフィルタBのそれぞれIDT
を設定すると、フィルタAのA1モード(0゜)とフィ
ルタBのB1モード(180゜)とは互いに逆相でその
共振周波数はほぼ等しくなる。更に、フィルタAのA3
モード(0゜)とフィルタBのB2モード(0゜)は同
位相でその共振周波数はほぼ等しくなる。以上にように
周波数と位相条件を設定した後、フィルタAとフィルタ
Bを電気的に並列接続するとA3モードの共振回路とB
2モードの共振回路が並列接続されて、周波数はほぼF
a3(=Fb2)でインピーダンス約1/2の共振回路
と等価となる。As shown in FIG. 1A, the filter B is
The electrode fingers of one of the two IDTs (the input side in FIG. 1A) are shifted by λ / 2 so as to have the opposite phase to the filter A. The filter A and the filter B are electrically connected in parallel to form a so-called resonance combined type SAW filter C. FIG. 1B shows transmission characteristics and phase characteristics when the terminal impedance of the filter A is mismatched, and FIG. 1C shows transmission characteristics and phase characteristics when the terminal impedance of the filter B is mismatched.
In order to change the frequency of each resonance point of the coupled multimode surface acoustic wave resonator, a method of changing the logarithm of the IDT, a method of shifting the input and output IDTs from a regularly arranged period, and a method of changing the electrodes are described. A known method such as a method of varying the film thickness may be appropriately combined. Here, FIG.
As shown in (c), the IDT of each of the filters A and B is set so that the relationship between the resonance frequencies of the filters A and B substantially satisfies the frequency relationship of Fa1 = Fb1 and Fa3 = Fb2.
Is set, the A1 mode (0 °) of the filter A and the B1 mode (180 °) of the filter B are out of phase with each other, and their resonance frequencies are substantially equal. Further, A3 of the filter A
The mode (0 °) and the B2 mode (0 °) of the filter B have the same phase and their resonance frequencies are almost equal. After setting the frequency and phase conditions as described above, when the filter A and the filter B are electrically connected in parallel, the resonance circuit of A3 mode and B
A two-mode resonance circuit is connected in parallel, and the frequency is almost F
a3 (= Fb2) is equivalent to a resonance circuit having an impedance of about 1/2.
【0010】更に、A1モード(0゜)の共振回路とB
1モード(180゜)の共振回路とが並列接続されると
位相が互いに逆相であるためこれらの回路を流れる電流
は互いに打ち消しあい、伝送特性上に減衰極が生ずるこ
とになる。例えば、この共振合成型SAWフィルタの終
端インピーダンスをミスマッチさせて伝送特性を測定す
ると図2(a)に示すように共振ピークが3個(Fb
3、Fa3、Fa2)存在し、Fa1(=Fb1)近傍
の矢印で示す位置に減衰極が存在することを確認するこ
とができる。そして、この共振合成型SAWフィルタの
終端インピーダンスを適切な値に設定すると図2(b)
に示すような濾波特性が得られる。図2(a)から明ら
かなように通過域はほぼ共振周波数Fb3からFa2ま
でであり、減衰極が通過帯域の高域側に生じるためカッ
トオフの高域側近傍の減衰傾度が急峻なフィルタを実現
することが可能である。図3に示す実線は上記した本発
明係る第1の実施例の濾波特性例であり、破線は従来の
構成の濾波特性例である。従来の共振合成型SAWフィ
ルタが中心周波数F0(=246MHz)+0.2MH
zで5dBの減衰量であるのに対し、本発明に係る第1
の実施例ではF0(=246MHz)+0.2MHzで
20dBの減衰量が得られ、高域側において減衰傾度が
大幅に改善されることがわかる。Further, the A1 mode (0 °) resonance circuit and B
If a 1-mode (180 °) resonance circuit is connected in parallel, the phases are opposite to each other, so that the currents flowing through these circuits cancel each other, and an attenuation pole is generated on the transmission characteristics. For example, when the transmission characteristics are measured by mismatching the terminal impedance of this resonance combined type SAW filter, as shown in FIG. 2A, three resonance peaks (Fb
3, Fa3, Fa2) and the presence of an attenuation pole at the position indicated by the arrow near Fa1 (= Fb1). When the terminating impedance of this resonance combined type SAW filter is set to an appropriate value, FIG.
As shown in FIG. As is clear from FIG. 2 (a), the pass band is substantially from the resonance frequency Fb3 to Fa2, and the attenuation pole is formed on the high band side of the pass band. It is possible to realize. The solid line shown in FIG. 3 is an example of the filtering characteristic of the first embodiment of the present invention, and the broken line is an example of the filtering characteristic of the conventional configuration. The conventional resonance combining type SAW filter has a center frequency F 0 (= 246 MHz) +0.2 MH
While the attenuation is 5 dB at z, the first
It can be seen that in the example of (1), an attenuation of 20 dB is obtained at F 0 (= 246 MHz) +0.2 MHz, and the attenuation gradient is greatly improved on the high frequency side.
【0011】図4は本発明の図1(a)の電極パターン
を用いた第2の実施例であって、図4(a)はフィルタ
Aの終端インピーダンスをミスマッチさせた場合の伝送
特性と位相特性であり、図4(b)はフィルタBの終端
インピーダンスをミスマッチさせた場合の伝送特性と位
相特性である。本実施例では、フィルタAの電極の位相
とフィルタBの電極の位相を互いに逆相に設定する。そ
の上で、フィルタAのA1モード(0゜)の共振周波数
Fa1とフィルタBのB1モード(180゜)の共振周
波数Fb1をほぼ等しくする。更に、フィルタAとフィ
ルタBとの他のモードの周波数関係は図4(a)、
(b)示すように互いに一致させず、フィルタBの共振
周波数Fb2とFb3の間にフィルタAの共振周波数F
a2とFa3を配置する。即ち、フィルタAとBの共振
周波数の関係をFb3<Fa3<Fa2<Fb2とす
る。このような周波数配列を有するフィルタAとBを電
気的に並列接続して構成した共振合成型SAWフィルタ
の終端インピーダンスをミスマッチさせると、図4
(c)に示すように4つの共振ピークが現れる。更に、
位相が互いに逆相で共振周波数がほぼ等しい周波数Fa
1(=Fb1)では減衰極が生ずることになる。図4
(d)は上記共振合成型SAWフィルタに適切な終端を
施した場合の濾波特性であり、通過帯域の高周波側のカ
ットオフ特性が急峻なフィルタが実現できる。FIG. 4 shows a second embodiment of the present invention using the electrode pattern of FIG. 1A. FIG. 4A shows transmission characteristics and phase when the terminal impedance of the filter A is mismatched. FIG. 4B shows transmission characteristics and phase characteristics when the terminal impedance of the filter B is mismatched. In this embodiment, the phase of the electrode of the filter A and the phase of the electrode of the filter B are set to be opposite to each other. Then, the resonance frequency Fa1 of the A1 mode (0 °) of the filter A is made substantially equal to the resonance frequency Fb1 of the B1 mode (180 °) of the filter B. Further, the frequency relationship between the other modes of the filter A and the filter B is shown in FIG.
(B) The resonance frequencies Fb2 and Fb3 of the filter B are not matched with each other as shown in FIG.
a2 and Fa3 are arranged. That is, the relationship between the resonance frequencies of the filters A and B is set to Fb3 <Fa3 <Fa2 <Fb2. When the terminal impedance of the resonance combined type SAW filter configured by electrically connecting the filters A and B having such a frequency arrangement in parallel is mismatched, FIG.
Four resonance peaks appear as shown in FIG. Furthermore,
A frequency Fa whose phases are opposite to each other and whose resonance frequencies are substantially equal.
At 1 (= Fb1), an attenuation pole occurs. FIG.
(D) shows the filtering characteristics when the resonance combining type SAW filter is appropriately terminated, and a filter having a sharp cutoff characteristic on the high frequency side of the pass band can be realized.
【0012】図5は本発明に係る図1(a)の電極パタ
ーンを用いた第3の実施例であって、フィルタAとフィ
ルタBの電極の位相を互いに逆相に設定する。更に、フ
ィルタAとフィルタBの各モードの共振周波数関係を図
5(a)、(b)に示すように配列する。即ち、フィル
タAのA2モードの共振周波数Fa2とフィルタBのB
1モードの共振周波数Fb1とをほぼ等しく、更にA3
モードの共振周波数Fa3とB3モードの共振周波数F
b3とをほぼ等しく設定する。以上のように設定すると
フィルタBのB2モードの共振周波数Fb2はフィルタ
Aの共振周波数Fa2とFa3の中間に配置されること
になる。フィルタAとフィルタBを電気的に並列接続し
て共振合成型SAWフィルタを構成し終端インピーダン
スをミスマッチさせるとその電送特性は図5(c)に示
すように3個の共振ピークと矢印で示す位置に減衰極が
生じる。該フィルタに適切な終端インピーダンスを施す
と、図5(d)に示すようにFb2からFa1までを通
過帯域とする低域側の減衰傾度が急峻なフィルタを得る
ことができる。FIG. 5 shows a third embodiment using the electrode pattern of FIG. 1A according to the present invention, wherein the phases of the electrodes of the filter A and the filter B are set to be opposite to each other. Further, the resonance frequency relation of each mode of the filter A and the filter B is arranged as shown in FIGS. 5 (a) and 5 (b). That is, the resonance frequency Fa2 of the A2 mode of the filter A and the B
The resonance frequency Fb1 of one mode is substantially equal to
Mode resonance frequency Fa3 and B3 mode resonance frequency F
b3 is set substantially equal. With the above setting, the resonance frequency Fb2 of the filter B in the B2 mode is arranged between the resonance frequencies Fa2 and Fa3 of the filter A. When the filter A and the filter B are electrically connected in parallel to form a resonance-combined SAW filter and the terminal impedances are mismatched, the transmission characteristics thereof become three resonance peaks and positions indicated by arrows as shown in FIG. , An attenuation pole occurs. When an appropriate terminal impedance is applied to the filter, a filter having a steep attenuation slope on the low frequency side having a pass band from Fb2 to Fa1 can be obtained as shown in FIG.
【0013】図6(a)は本発明に係る第4の実施例を
示す電極パターンの模式的平面図であって、圧電基板1
の主面上に、IDT6a、6b、6cと反射器7a、7
bとで構成する縦結合三重モードSAWフィルタA(フ
ィルタA)を配置し、更にIDT8a、8b、8cと反
射器9a、9bとで構成する縦結合三重モードSAWフ
ィルタB(フィルタB)を配置する。図6(a)に示す
ような電極パターンを構成するとフィルタAとフィルタ
Bとの位相は同相となる。ここで、フィルタA、Bを電
気的に並列接続して共振合成型SAWフィルタを構成す
る場合を考える。図6(b)はフィルタAの終端インピ
ーダンスをミスマッチさせた場合の伝送特性と位相特性
であり、図6(c)はフィルタBの終端抵抗をミスマッ
チさせた場合の伝送特性と位相特性である。図6
(b)、(c)に示すようにフィルタAのA1(1次)
モードの共振周波数Fa1とフィルタBのB1(1次)
モードの共振モードの共振周波数をほぼ一致させる。フ
ィルタAのA3モードの共振周波数Fa3とフィルタB
のB2モードの共振周波数Fb2をほぼ等しくする。更
に、フィルタAとフィルタBを電気的に並列接続して共
振合成型SAWフィルタを構成し、該フィルタの終端イ
ンピーダンスをミスマッチさせると図7(a)の伝送特
性と位相特性が得られる。該フィルタに適切な終端を施
すと図7(b)に示すようにA3モードの共振周波数と
B2モードの共振周波数がほぼ等しく、位相が互いに逆
相であるため、Fa3(=Fb2)の周波数に減衰極が
生じ、通過域がFa2からFa1(=Fb1)まであ
り、通過帯域の低域側の減衰傾度が急峻なフィルタを得
ることができる。FIG. 6A is a schematic plan view of an electrode pattern showing a fourth embodiment according to the present invention.
IDTs 6a, 6b, 6c and reflectors 7a, 7
b, and a longitudinally coupled triple mode SAW filter B (filter B) composed of IDTs 8a, 8b, 8c and reflectors 9a, 9b is disposed. . When the electrode pattern as shown in FIG. 6A is formed, the phases of the filter A and the filter B are in phase. Here, a case is considered in which filters A and B are electrically connected in parallel to form a resonance-combined SAW filter. FIG. 6B shows the transmission characteristics and phase characteristics when the terminal impedance of the filter A is mismatched, and FIG. 6C shows the transmission characteristics and phase characteristics when the terminal resistance of the filter B is mismatched. FIG.
As shown in (b) and (c), A1 (primary) of filter A
Mode resonance frequency Fa1 and filter B B1 (primary)
The resonance frequencies of the resonance modes of the modes are substantially matched. A3 mode resonance frequency Fa3 of filter A and filter B
B2 mode resonance frequency Fb2 is made substantially equal. Further, the filter A and the filter B are electrically connected in parallel to form a resonance-combined SAW filter, and when the terminal impedance of the filter is mismatched, the transmission characteristics and phase characteristics of FIG. 7A are obtained. When the filter is appropriately terminated, the resonance frequency of the A3 mode and the resonance frequency of the B2 mode are substantially equal and the phases are opposite to each other as shown in FIG. 7B, so that the frequency of Fa3 (= Fb2) is reduced. An attenuation pole is generated, the passband is from Fa2 to Fa1 (= Fb1), and a filter having a steep attenuation slope on the lower side of the passband can be obtained.
【0014】図8は本発明に係る第5の実施例であり、
横結合二重モードSAWフィルタを2つ(フィルタA、
B)並列接続して構成する共振合成型SAWフィルタに
関する。フィルタAとフィルタBの位相は逆相になるよ
うにIDTの電極指をλ/2だけずらして配置し、図9
(a)に示すようにフィルタAのA1(1次)、A2
(2次)モードの共振周波数をFa1、Fa2とする。
同様に図9(b)に示すように、フィルタBのB1(1
次)、B2(2次)モードの共振周波数をFb1、Fb
2とする。ここでフィルタAのA2モードの共振周波数
Fa2とフィルタBのB2モードの共振周波数Fb2を
ほぼ等しく設定する。IDTの設定条件より上記2つの
モードの位相は互いに逆相となる。図9(c)はフィル
タAとフィルタBを電気的に並列接続して構成する共振
結合型SAWフィルタの終端インピーダンスをミスマッ
チさせた場合の伝送特性と位相特性であり、2つの共振
ピークと周波数Fa2(=Fb2)に矢印で示す減衰極
が生じる。該フィルタに適切な終端条件を施した場合の
濾波特性が図9(d)であり、通過域はFb1からFa
1までとなる。 図9(c)、(d)に示すように通過
域の低域側の共振周波数Fa2(Fb2)に矢印で示す
減衰極が生ずるのは、A2モードの共振周波数Fa2と
B2モードの共振周波数はほぼ等しく位相が互いに逆相
のため、流れる電流が互いに打ち消し合うからである。
この手段を用いると図9(d)に示すごとく通過帯域の
低域側の減衰傾度が急峻なフィルタを実現することがで
きる。FIG. 8 shows a fifth embodiment according to the present invention.
Two laterally coupled dual mode SAW filters (Filter A,
B) The present invention relates to a resonance combined type SAW filter configured by connecting in parallel. The electrode fingers of the IDT are shifted by λ / 2 so that the phases of the filter A and the filter B are opposite to each other.
As shown in (a), A1 (primary), A2 of filter A
The resonance frequencies of the (secondary) mode are Fa1 and Fa2.
Similarly, as shown in FIG. 9B, B1 (1
Next, the resonance frequencies of the B2 (secondary) mode are represented by Fb1 and Fb.
Let it be 2. Here, the resonance frequency Fa2 of the A2 mode of the filter A and the resonance frequency Fb2 of the B2 mode of the filter B are set substantially equal. According to the setting conditions of the IDT, the phases of the above two modes are opposite to each other. FIG. 9C shows transmission characteristics and phase characteristics when the terminal impedance of the resonance-coupling type SAW filter configured by electrically connecting the filter A and the filter B in parallel is different, and shows two resonance peaks and a frequency Fa2. An attenuation pole indicated by an arrow is generated at (= Fb2). FIG. 9D shows the filtering characteristics when an appropriate termination condition is applied to the filter, and the passband ranges from Fb1 to Fa.
Up to 1. As shown in FIGS. 9C and 9D, an attenuation pole indicated by an arrow is generated in the resonance frequency Fa2 (Fb2) on the lower side of the passband because the resonance frequency Fa2 in the A2 mode and the resonance frequency in the B2 mode are different from each other. This is because the flowing currents cancel each other out because the phases are almost equal and opposite to each other.
By using this means, it is possible to realize a filter having a steep attenuation slope on the lower side of the pass band as shown in FIG.
【0015】図10は本発明に係る第6の実施例であ
る。図10(a)は縦結合三重モードSAWフィルタ
(フィルタA)の周波数配列と位相を示す図であり、同
(b)は縦結合二重モードSAWフィルタ(フィルタ
B)の周波数配列と位相を示す図である。フィルタAの
A1(1次)モードの共振周波数Fa1とフィルタBの
B1(1次)モードの共振周波数Fb1をほぼ一致さ
せ、且つ前記1次モード同士の位相が同相になるように
IDTを配置する。更に、フィルタAのA3(3次)モ
ードの共振周波数Fa3とフィルタBのB2(2次)モ
ードの共振周波数Fb2をほぼ等しく設定する。A3モ
ードの位相は0°であり、B2モードの位相は180°
と互いに逆相となる。このにように設定したフィルタA
とフィルタBを電気的に並列接続して共振合成型SAW
フィルタの終端インピーダンスをミスマッチさせると図
10(c)の伝送特性と位相特性が得られる。A3モー
ドとB2モードとは共振周波数がほぼ等しく位相が逆相
に設定されているため、図10(c)の矢印で示すよう
に通過域の低域側に減衰極を生じさせることが可能であ
り、前記フィルタに適切な終端を施すことにより図10
(d)に示す濾波特性のフィルタが得られ、通過帯域の
低域側の減衰傾度が急峻なフィルタを実現することがで
きる。FIG. 10 shows a sixth embodiment according to the present invention. FIG. 10A is a diagram showing a frequency arrangement and a phase of a longitudinally coupled triple mode SAW filter (filter A), and FIG. 10B is a view showing a frequency arrangement and a phase of a longitudinally coupled dual mode SAW filter (filter B). FIG. The IDT is arranged such that the resonance frequency Fa1 of the A1 (first-order) mode of the filter A and the resonance frequency Fb1 of the B1 (first-order) mode of the filter B are substantially the same, and the phases of the first-order modes are in phase. . Further, the resonance frequency Fa3 of the A3 (tertiary) mode of the filter A and the resonance frequency Fb2 of the B2 (secondary) mode of the filter B are set substantially equal. The phase of the A3 mode is 0 °, and the phase of the B2 mode is 180 °.
And the phases are opposite to each other. Filter A set in this way
And filter B are electrically connected in parallel to each other to form a resonance-combined SAW
When the terminal impedance of the filter is mismatched, the transmission characteristics and the phase characteristics shown in FIG. Since the A3 mode and the B2 mode have substantially the same resonance frequency and opposite phases, an attenuation pole can be generated on the lower side of the passband as shown by the arrow in FIG. With appropriate termination of the filter,
As a result, a filter having the filtering characteristic shown in (d) can be obtained, and a filter having a steep attenuation gradient on the lower side of the pass band can be realized.
【0016】図11は本発明に係る図1(a)に示す電
極パターンを用いた第7の実施例の周波数配列、位相関
係及び濾波特性を示す図である。図11(a)は縦結合
三重モードSAWフィルタ(フィルタA)の終端抵抗を
ミスマッチさせた伝送特性であり、フィルタAのA1か
らA3モードの共振周波数とその位相を示している。図
11(b)はフィルタAと逆相になるようにIDTを設
定した縦結合三重モードSAWフィルタ(フィルタB)
の終端抵抗をミスマッチさせた伝送特性であり、フィル
タBのB1モードからB3モードの共振周波数とその位
相を示している。フィルタAのA1、A3モードとフィ
ルタBのB1、B3モードのそれぞれの対応する共振周
波数をほぼ等しく設定し、それぞれのモードの位相関係
はIDTの設定により互いに逆相になるように設定され
ている。フィルタA、Bを電気的に並列接続して共振合
成型SAWフィルタを構成し、該フィルタの終端インピ
ーダンスをミスマッチさせると図11(c)に示す伝送
特性が得られ、Fa3とFa1に減衰極を有する特性と
なる。該フィルタに適切な終端を施せば図11(d)に
示すように通過域はFa2からFb2までであり、低域
側及び高域側に急峻な減衰特性を有するフィルタを実現
することができる。FIG. 11 is a view showing a frequency arrangement, a phase relationship and a filtering characteristic of a seventh embodiment using the electrode pattern shown in FIG. 1A according to the present invention. FIG. 11A shows transmission characteristics in which the terminating resistance of a longitudinally coupled triple mode SAW filter (filter A) is mismatched, and shows the resonance frequencies of A1 to A3 modes of the filter A and their phases. FIG. 11B shows a longitudinally coupled triple mode SAW filter (filter B) in which an IDT is set so as to have a phase opposite to that of the filter A.
, And shows the resonance frequency and the phase of the filter B from the B1 mode to the B3 mode. The corresponding resonance frequencies of the A1 and A3 modes of the filter A and the B1 and B3 modes of the filter B are set substantially equal, and the phase relation of each mode is set to be opposite to each other by setting the IDT. . When filters A and B are electrically connected in parallel to form a resonance-combined SAW filter, and the terminal impedance of the filter is mismatched, the transmission characteristics shown in FIG. 11C are obtained, and the attenuation poles are formed at Fa3 and Fa1. Characteristics. If the filter is appropriately terminated, the passband is from Fa2 to Fb2 as shown in FIG. 11D, and a filter having a steep attenuation characteristic in the low band side and the high band side can be realized.
【0017】以上説明した第1の実施例から第7の実施
例を用いれば、縦続段数を減らすことができるため、従
来の多段従属接続構成の場合に必要とされた段間のリア
クタンス素子を用いることなく同等の特性のフィルタを
実現することが可能となる。本発明により減衰極を発生
させる周波数を容易に制御することができるため設計自
由度が大幅に広げられた。また本発明によるフィルタを
図12のごとく多段縦続接続すれば更に急峻なフィルタ
を実現することが可能であり、そのため段間に必要とな
るリアクタンス素子Xの数を従来の構成よりも少なくす
ることができる。If the first to seventh embodiments described above are used, the number of cascaded stages can be reduced. Therefore, a reactance element between stages required in a conventional multistage cascade connection configuration is used. It is possible to realize a filter having the same characteristics without using the filter. According to the present invention, the frequency at which the attenuation pole is generated can be easily controlled, so that the degree of freedom in design is greatly expanded. Further, if the filter according to the present invention is cascaded in multiple stages as shown in FIG. 12, it is possible to realize a steeper filter, so that the number of reactance elements X required between stages can be reduced as compared with the conventional configuration. it can.
【0018】以上、本発明に用いる2つのSAW共振器
フィルタとして主として縦結合型SAWフィルタを例に
挙げて説明したが、本発明はこれのみに限定されるもの
ではなく図8、図13及び図14に示すようにフィルタ
AとフィルタBが横結合SAW共振器フィルタである場
合や図15のようにフィルタAとフィルタBが二次元モ
ード結合SAW共振器フィルタである場合についても適
用可能であり、更にはフィルタAが縦結合SAW共振器
フィルタで、フィルタBが横結合SAW共振器フィルタ
である場合のようにフィルタAとフィルタBが異な種類
のSAW共振器フィルタでも本発明は同様に適用でき
る。また、平衡入出力型としたSAWフィルタの場合に
おいても本発明は同様に適用できることは云うまでもな
い。As described above, the vertical coupling type SAW filter has been mainly described as an example of the two SAW resonator filters used in the present invention. However, the present invention is not limited to this, and FIGS. Also, the present invention can be applied to a case where the filter A and the filter B are laterally coupled SAW resonator filters as shown in FIG. 14 and a case where the filter A and the filter B are two-dimensional mode coupled SAW resonator filters as shown in FIG. Further, the present invention can be similarly applied to a SAW resonator filter having different types of filters A and B as in the case where the filter A is a longitudinally coupled SAW resonator filter and the filter B is a horizontally coupled SAW resonator filter. Further, it goes without saying that the present invention can be similarly applied to a balanced input / output type SAW filter.
【0019】[0019]
【発明の効果】本発明は、以上説明したように構成した
ので、従来の共振合成型SAWフィルタ比べ減衰傾度の
はるかに優れたSAWフィルタを実現することが可能で
あり、最近のデジタル通信方式のフィルタの要求を十分
に満たすことができる。更に、従来は減衰傾度を急峻に
するため縦続接続していた特性が段数の少ないフィルタ
で実現することができ、挿入損失を大幅に小さくするこ
とができた。Since the present invention is configured as described above, it is possible to realize a SAW filter having a much better attenuation gradient than a conventional resonance combined type SAW filter. The requirements of the filter can be sufficiently satisfied. Furthermore, the characteristics that were conventionally connected in cascade in order to make the attenuation gradient steep can be realized with a filter having a small number of stages, and the insertion loss can be significantly reduced.
【図1】本発明に係る共振合成型SAWフィルタの実施
の一形態例で、(a)は電極パターンの模式的平面図、
(b)、(c)はフィルタA、Bのそれぞれの共振周波
数配列と位相関係を示す図である。FIG. 1A is a schematic plan view of an electrode pattern according to an embodiment of a resonance synthesis type SAW filter according to the present invention.
(B), (c) is a figure which shows each resonance frequency arrangement | sequence of filter A and B, and a phase relationship.
【図2】(a)は共振合成型SAWフィルタの周波数配
列と位相関係、(b)は濾波特性を示す図である。2A is a diagram illustrating a frequency arrangement and a phase relationship of a resonance-combined SAW filter, and FIG. 2B is a diagram illustrating a filtering characteristic.
【図3】実線は本発明に係る第1の実施例の濾波特性、
波線は比較のための従来の濾波特性例である。FIG. 3 is a solid line showing the filtering characteristics of the first embodiment according to the present invention;
A dashed line is an example of a conventional filtering characteristic for comparison.
【図4】(a)、(b)は第2の実施例のフィルタA、
Bのそれぞれ周波数配列と位相関係、(c)、(d)は
共振合成型SAWフィルタ伝送特性と濾波特性である。FIGS. 4A and 4B show a filter A according to a second embodiment;
B shows the frequency arrangement and phase relationship, and (c) and (d) show the transmission characteristics and the filtering characteristics of the resonance combined type SAW filter.
【図5】(a)、(b)は第3の実施例のフィルタA、
Bのそれぞれ周波数配列と位相関係、(c)、(d)は
共振合成型SAWフィルタの伝送特性と濾波特性であ
る。FIGS. 5A and 5B show a filter A according to a third embodiment;
B shows the frequency arrangement and phase relationship, and (c) and (d) show the transmission characteristics and the filtering characteristics of the resonance-combined SAW filter.
【図6】本発明に係る第4の実施例で、(a)は電極パ
ターンの模式的平面図、(b)、(c)はフィルタA、
Bのそれぞれの共振周波数配列と位相関係を示す図であ
る。6A is a schematic plan view of an electrode pattern according to a fourth embodiment of the present invention, FIG. 6B and FIG.
FIG. 6 is a diagram showing the respective resonance frequency arrangements and phase relationships of B.
【図7】本発明の第4の実施例で、(a)、(b)はそ
れぞれ共振合成型SAWフィルタの伝送特性と濾波特性
を示す図である。FIGS. 7A and 7B are diagrams illustrating a transmission characteristic and a filtering characteristic of a resonance combined type SAW filter according to a fourth embodiment of the present invention.
【図8】2つの横結合二重モードフィルタを並列接続し
た共振合成型SAWフィルタの電極パターンの模式的平
面図である。FIG. 8 is a schematic plan view of an electrode pattern of a resonance combined type SAW filter in which two transversely coupled dual mode filters are connected in parallel.
【図9】本発明の第5の実施例で、(a)、(b)はフ
ィルタA、Bのそれぞれの共振周波数配列と位相関係を
示す図、(c)、(d)は共振合成型SAWフィルタの
伝送特性と濾波特性を示す図である。9 (a) and 9 (b) are diagrams showing respective resonance frequency arrays and phase relationships of filters A and B in the fifth embodiment of the present invention, and FIGS. 9 (c) and 9 (d) are resonance composite type. FIG. 3 is a diagram illustrating transmission characteristics and filtering characteristics of a SAW filter.
【図10】本発明の第6の実施例で、(a)、(b)は
フィルタA、Bのそれぞれの共振周波数配列と位相関係
を示す図、(c)、(d)は共振合成型SAWフィルタ
の伝送特性と濾波特性を示す図である。10 (a) and 10 (b) are diagrams showing the respective resonance frequency arrangements and phase relationships of filters A and B in the sixth embodiment of the present invention, and FIGS. FIG. 3 is a diagram illustrating transmission characteristics and filtering characteristics of a SAW filter.
【図11】本発明の第7の実施例で、(a)、(b)は
フィルタA、Bのそれぞれの共振周波数配列と位相関係
を示す図、(c)、(d)は共振合成型SAWフィルタ
の伝送特性と濾波特性を示す図である。11A and 11B are diagrams showing resonance frequency arrangements and phase relationships of filters A and B in the seventh embodiment of the present invention, and FIGS. 11C and 11D are resonance combination types. FIG. 3 is a diagram illustrating transmission characteristics and filtering characteristics of a SAW filter.
【図12】本発明に係る二縦続属接続共振合成型SAW
フィルタを示す図である。FIG. 12 shows a two-cascade connection resonance combined SAW according to the present invention.
It is a figure showing a filter.
【図13】横結合二重モードSAWフィルタを用いて構
成した共振合成型SAWフィルタの例である。FIG. 13 is an example of a resonance-combined SAW filter configured using a laterally coupled dual-mode SAW filter.
【図14】横結合三重モードSAWフィルタを用いて構
成した共振合成型SAWフィルタの例である。FIG. 14 is an example of a resonance-combined SAW filter configured using a laterally coupled triple mode SAW filter.
【図15】フィルタA、Bが二次元モード結合SAWフ
ィルタの電極パターンを示す図である。FIG. 15 is a view showing an electrode pattern of a two-dimensional mode-coupled SAW filter in which filters A and B are provided.
【図16】従来の共振合成型SAWフィルタで、(a)
は模式的電極パターンを示す図、(b)、(c)はそれ
ぞれフィルタA、Bの周波数配列と位相関係を示す図、
(d)は共振合成型SAWフィルタの伝送特性を示す図
である。FIG. 16 shows a conventional resonance-combination type SAW filter, (a).
Is a diagram showing a schematic electrode pattern, (b) and (c) are diagrams showing a frequency arrangement and a phase relationship of filters A and B, respectively.
(D) is a diagram illustrating the transmission characteristics of the resonance-combined SAW filter.
【図17】2つの縦結合型三重モードフィルタを並列接
続した共振合成型SAWフィルタの濾波特性αと遅延特
性βを示す図である。FIG. 17 is a diagram showing a filtering characteristic α and a delay characteristic β of a resonance combined type SAW filter in which two longitudinally coupled triple mode filters are connected in parallel.
1・・圧電基板2a、2b、2c、4a、4b、4c、
6a、6b、6c・・IDT 8a、8b、8c・・IDT 3a、3b、5a、5b、7a、7b、9a、9b・・
反射器 Fa1・・フィルタAの1次モードの共振周波数 Fa2・・フィルタAの2次モードの共振周波数 Fa3・・フィルタAの3次モードの共振周波数 Fb1・・フィルタBの1次モードの共振周波数 Fb2・・フィルタBの2次モードの共振周波数 Fb3・・フィルタBの3次モードの共振周波数 0°、180°・・モードの位相 X・・リアクタンス素子1. Piezoelectric substrates 2a, 2b, 2c, 4a, 4b, 4c,
6a, 6b, 6c IDT 8a, 8b, 8c IDT 3a, 3b, 5a, 5b, 7a, 7b, 9a, 9b
Reflector Fa1 Resonant frequency of the first-order mode of filter A Fa2 Resonant frequency of the second-order mode of filter A Fa3 Resonant frequency of the third-order mode of filter A Fb1 Resonant frequency of the first-order mode of filter B Fb2: Resonance frequency of second-order mode of filter B Fb3: Resonance frequency of third-order mode of filter B 0 °, 180 ° -mode phase X: Reactance element
Claims (9)
その最外側に反射器を配置し励起される表面波の音響結
合を利用して構成した結合型多重モードSAWフィルタ
を少なくとも2個併置し電気的に並列接続して構成した
共振合成型SAWフィルタにおいて、前記結合型多重モ
ードSAWフィルタの一方の多重モードSAWフィルタ
が有する振動モードの少なくとも1つと、他方の多重モ
ードSAWフィルタが有する振動モードの少なくとも1
つとが、互いに共振周波数が等しく、且つ該共振周波数
における入出力間位相シフト量が(2n+1)π(n=
0,1,2・・)異なることを特徴とする有極型弾性表
面波フィルタ。1. At least two coupled multimode SAW filters each having at least two IDTs disposed on a piezoelectric substrate and a reflector on the outermost side thereof and utilizing acoustic coupling of a surface wave to be excited. In a resonance combined type SAW filter electrically connected in parallel, at least one of the vibration modes of one of the coupled multi-mode SAW filters and the vibration mode of the other multi-mode SAW filter. At least one
And the resonance frequency is equal to each other, and the phase shift amount between the input and output at the resonance frequency is (2n + 1) π (n =
0, 1,...) Which are different from each other.
多重モードSAWフィルタであることを特徴とする請求
項1記載の有極型弾性表面波フィルタ。2. The polarized surface acoustic wave filter according to claim 1, wherein the multi-mode SAW filter is a longitudinally-coupled multi-mode SAW filter.
板上に表面波の伝搬方向に沿って入出力IDTとその両
側に反射器を配置し該入出力IDT間にグレーティング
を配して構成した縦結合多重モードSAWフィルタであ
ることを特徴とする請求項1記載の有極型弾性表面波フ
ィルタ。3. A longitudinal coupling in which the multi-mode SAW filter is formed by arranging an input / output IDT on a piezoelectric substrate along a propagation direction of a surface acoustic wave and reflectors on both sides thereof and arranging a grating between the input / output IDTs. 2. The polarized surface acoustic wave filter according to claim 1, wherein the surface acoustic wave filter is a multi-mode SAW filter.
多重モードSAWフィルタであることを特徴とする請求
項1記載の有極型弾性表面波フィルタ。4. The polarized surface acoustic wave filter according to claim 1, wherein the multi-mode SAW filter is a transversely coupled multi-mode SAW filter.
の伝搬方向の結合を利用した縦モード共振と、伝搬方向
に垂直な横モード共振とを結合させた二次元モード結合
多重モードSAWフィルタであることを特徴とする請求
項1記載の有極型弾性表面波フィルタ。5. The multi-mode SAW filter, wherein the multi-mode SAW filter is a two-dimensional mode-coupled multi-mode SAW filter combining longitudinal mode resonance utilizing coupling in the propagation direction of a surface wave and transverse mode resonance perpendicular to the propagation direction. The polarized surface acoustic wave filter according to claim 1, wherein:
一方が縦結合多重モードSAWフィルタで他方が横結合
多重モードSAWフィルタであることを特徴とする請求
項1記載の有極型弾性表面波フィルタ。6. The polarized surface acoustic wave filter according to claim 1, wherein one of the multimode SAW resonator filters is a longitudinally coupled multimode SAW filter and the other is a laterally coupled multimode SAW filter.
縦結合多重モードSAWフィルタで他方が二次元モード
結合多重モードSAWフィルタであることを特徴とする
請求項1記載の有極型弾性表面波フィルタ。7. The polarized surface acoustic wave filter according to claim 1, wherein one of the multimode SAW filters is a longitudinally coupled multimode SAW filter and the other is a two-dimensional mode coupled multimode SAW filter.
横結合多重モードSAWフィルタで他方が二次元モード
結合多重モードSAWフィルタであることを特徴とする
請求項1記載の有極型弾性表面波フィルタ。8. The polarized surface acoustic wave filter according to claim 1, wherein one of the multi-mode SAW filters is a laterally coupled multi-mode SAW filter and the other is a two-dimensional mode coupled multi-mode SAW filter.
性表面波フィルタを少なくとも1つ用いて縦続構成した
ことを特徴とする有極型弾性表面波フィルタ。9. A polarized surface acoustic wave filter comprising a cascade configuration using at least one polarized surface acoustic wave filter according to claim 1.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11618097A JPH10294644A (en) | 1997-04-18 | 1997-04-18 | Polar surface acoustic wave device |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11618097A JPH10294644A (en) | 1997-04-18 | 1997-04-18 | Polar surface acoustic wave device |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH10294644A true JPH10294644A (en) | 1998-11-04 |
Family
ID=14680792
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP11618097A Pending JPH10294644A (en) | 1997-04-18 | 1997-04-18 | Polar surface acoustic wave device |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH10294644A (en) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6842090B2 (en) * | 1999-10-04 | 2005-01-11 | Kabushiki Kaisha Toshiba | Surface acoustic wave device utilizing opposite propagation direction regions and resonant mode coupling |
KR100485734B1 (en) * | 2001-10-12 | 2005-04-28 | 가부시키가이샤 무라타 세이사쿠쇼 | Surface acoustic wave device and communication device |
KR100493215B1 (en) * | 2001-08-29 | 2005-06-03 | 가부시키가이샤 무라타 세이사쿠쇼 | Surface acoustic wave filter |
US9325046B2 (en) | 2012-10-25 | 2016-04-26 | Mesaplexx Pty Ltd | Multi-mode filter |
US9401537B2 (en) | 2011-08-23 | 2016-07-26 | Mesaplexx Pty Ltd. | Multi-mode filter |
US9406988B2 (en) | 2011-08-23 | 2016-08-02 | Mesaplexx Pty Ltd | Multi-mode filter |
US9614264B2 (en) | 2013-12-19 | 2017-04-04 | Mesaplexxpty Ltd | Filter |
US9843083B2 (en) | 2012-10-09 | 2017-12-12 | Mesaplexx Pty Ltd | Multi-mode filter having a dielectric resonator mounted on a carrier and surrounded by a trench |
-
1997
- 1997-04-18 JP JP11618097A patent/JPH10294644A/en active Pending
Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6842090B2 (en) * | 1999-10-04 | 2005-01-11 | Kabushiki Kaisha Toshiba | Surface acoustic wave device utilizing opposite propagation direction regions and resonant mode coupling |
KR100493215B1 (en) * | 2001-08-29 | 2005-06-03 | 가부시키가이샤 무라타 세이사쿠쇼 | Surface acoustic wave filter |
KR100485734B1 (en) * | 2001-10-12 | 2005-04-28 | 가부시키가이샤 무라타 세이사쿠쇼 | Surface acoustic wave device and communication device |
US9559398B2 (en) | 2011-08-23 | 2017-01-31 | Mesaplex Pty Ltd. | Multi-mode filter |
US9401537B2 (en) | 2011-08-23 | 2016-07-26 | Mesaplexx Pty Ltd. | Multi-mode filter |
US9406988B2 (en) | 2011-08-23 | 2016-08-02 | Mesaplexx Pty Ltd | Multi-mode filter |
US9406993B2 (en) | 2011-08-23 | 2016-08-02 | Mesaplexx Pty Ltd | Filter |
US9437916B2 (en) | 2011-08-23 | 2016-09-06 | Mesaplexx Pty Ltd | Filter |
US9437910B2 (en) | 2011-08-23 | 2016-09-06 | Mesaplexx Pty Ltd | Multi-mode filter |
US9698455B2 (en) | 2011-08-23 | 2017-07-04 | Mesaplex Pty Ltd. | Multi-mode filter having at least one feed line and a phase array of coupling elements |
US9843083B2 (en) | 2012-10-09 | 2017-12-12 | Mesaplexx Pty Ltd | Multi-mode filter having a dielectric resonator mounted on a carrier and surrounded by a trench |
US9325046B2 (en) | 2012-10-25 | 2016-04-26 | Mesaplexx Pty Ltd | Multi-mode filter |
US9614264B2 (en) | 2013-12-19 | 2017-04-04 | Mesaplexxpty Ltd | Filter |
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