JPH08330897A - Surface acoustic wave filter - Google Patents
Surface acoustic wave filterInfo
- Publication number
- JPH08330897A JPH08330897A JP12993995A JP12993995A JPH08330897A JP H08330897 A JPH08330897 A JP H08330897A JP 12993995 A JP12993995 A JP 12993995A JP 12993995 A JP12993995 A JP 12993995A JP H08330897 A JPH08330897 A JP H08330897A
- Authority
- JP
- Japan
- Prior art keywords
- comb
- electrode
- acoustic wave
- surface acoustic
- resonator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、高周波デバイスとして
好適な弾性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 suitable as a high frequency device.
【０００２】[0002]
【従来の技術】近年の携帯電話や自動車電話の普及に伴
い、小型・高性能の高周波フィルタの必要性が高まって
いる。高周波フィルタとしては、従来より、誘電体フィ
ルタや弾性表面波フィルタが知られているが、後者の弾
性表面波フィルタの方が小型・高性能化に適している。2. Description of the Related Art With the widespread use of mobile phones and car phones in recent years, there is an increasing need for compact high-performance high frequency filters. As a high frequency filter, a dielectric filter and a surface acoustic wave filter have been conventionally known, but the latter surface acoustic wave filter is more suitable for miniaturization and higher performance.
【０００３】また、弾性表面波フィルタは、電極構造に
より、多重電極型、多重モード型、或いは複合型（ラダ
ー接続型）等があり、それぞれ８００ＭＨｚ以上の周波
数においてバンドパスフィルタを実現できるが、低損失
で整合回路が不要であるという点から、複合型の弾性表
面波フィルタが注目されている。The surface acoustic wave filter may be of a multi-electrode type, a multi-mode type, a composite type (ladder connection type) or the like depending on the electrode structure, and a band pass filter can be realized at a frequency of 800 MHz or more, but it is low. A composite type surface acoustic wave filter is drawing attention because it does not require a matching circuit due to loss.
【０００４】この複合型の弾性表面波フィルタは、図８
に示すように、圧電基板（LiNbO3等）１上に櫛型電極２
ａとグレーティング反射器２ｂ，２ｂとから成る１ポー
ト共振器２を２つ備えたものを一つのフィルタ機能単位
３とするものであり、一方の１ポート共振器２を信号線
４に電気的に直列に接続し（これを直列腕共振器２Ｓと
いう）、他方の１ポート共振器２を信号線に電気的に並
列に接続している（これを並列腕共振器２Ｐという）。
なお、図９は、一つのフィルタ機能単位３の基本構成を
示している。This composite type surface acoustic wave filter is shown in FIG.
As shown in, the comb-shaped electrode 2 is formed on the piezoelectric substrate (LiNbO 3 etc.) 1.
One filter function unit 3 is provided with two 1-port resonators 2 each including a and a grating reflector 2b, 2b, and one of the 1-port resonators 2 is electrically connected to the signal line 4. They are connected in series (this is called a series arm resonator 2S), and the other one-port resonator 2 is electrically connected in parallel to the signal line (this is called a parallel arm resonator 2P).
Note that FIG. 9 shows the basic configuration of one filter function unit 3.
【０００５】複合型の弾性表面波フィルタは、前記の直
列腕共振器２Ｓと並列腕共振器２Ｐのインピーダンスの
差を利用してバンドパスフィルタを実現している。以
下、その原理を図１０（ａ）（ｂ）により簡単に述べ
る。直列腕共振器２ＳのインピーダンスをｊＸS 、並列
腕共振器２ＰのインピーダンスをｊＸP 、並列腕共振器
２Ｐの反共振周波数をｆap、その共振周波数をｆrP、直
列腕共振器２Ｓの反共振周波数をｆaS、その共振周波数
をｆrSとし、同図（ａ）に示すように、反共振周波数ｆ
apと共振周波数ｆrSとを略一致させることにより、同図
（ｂ）に示すように、その略一致点を中心とし、反共振
周波数ｆaS及び共振周波数ｆrPを極としたフィルタ特性
が得られる。The composite type surface acoustic wave filter realizes a bandpass filter by utilizing the difference in impedance between the series arm resonator 2S and the parallel arm resonator 2P. The principle will be briefly described below with reference to FIGS. The impedance of the series arm resonator 2S is jX S , the impedance of the parallel arm resonator 2P is jX P , the antiresonance frequency of the parallel arm resonator 2P is f ap , the resonance frequency thereof is f rP , and the antiresonance of the series arm resonator 2S. Assuming that the frequency is f aS and the resonance frequency thereof is f rS , as shown in FIG.
By making ap and the resonance frequency f rS substantially coincident with each other, a filter characteristic having an antiresonance frequency f aS and a resonance frequency f rP as poles is obtained with the substantially coincident point as the center, as shown in FIG. To be
【０００６】共振器２の個数は、フィルタの挿入損失、
帯域外抑圧量等に基づいて設定されるが、直列腕共振器
２Ｓを３個、並列腕共振器２Ｐを３個用いてフィルタ機
能単位３を３段に設けた構造で、圧電基板１として３６
°Ｙ−Ｘ（ＹカットＸ軸伝搬）のLiTaO3を用いると、８
００ＭＨｚ帯において最小挿入損失が２ｄＢ以下で帯域
外抑圧が２５ｄＢ以上の低損失フィルタが得られてい
る。また、この構造であれば、通過帯域において直列腕
共振器２Ｓのインピーダンスが０で並列腕共振器２Ｐの
インピーダンスが５０Ωより十分大きくなることから、
インピーダンス整合が図れ、整合回路が不要であるとい
う利点を有している。The number of resonators 2 depends on the insertion loss of the filter,
Although it is set based on the amount of out-of-band suppression or the like, it has a structure in which the filter function unit 3 is provided in three stages by using three series arm resonators 2S and three parallel arm resonators 2P.
If LiTaO 3 of ° Y-X (Y-cut X-axis propagation) is used, 8
A low-loss filter having a minimum insertion loss of 2 dB or less and an out-of-band suppression of 25 dB or more is obtained in the 00 MHz band. Further, with this structure, the impedance of the series arm resonator 2S is 0 and the impedance of the parallel arm resonator 2P is sufficiently larger than 50Ω in the pass band,
It has an advantage that impedance matching can be achieved and a matching circuit is unnecessary.
【０００７】ところで、複合型の弾性表面波フィルタで
は、そのフィルタ原理により、帯域幅を変化させるため
の自由度が小さいという欠点がある。即ち、直列腕共振
器２Ｓの共振周波数ｆrSと並列腕共振器２Ｐの反共振周
波数ｆapとを略一致させることが重要であり、共振周波
数ｆrSと反共振周波数ｆapとを略一致させないで帯域幅
の大きいフィルタを得ようとすると、図１１（ａ）
（ｂ）に示すように、共振周波数の差Δｆ（ｆrS−
ｆrP）を大きくしなければならず、この場合には、反共
振周波数ｆapと共振周波数ｆrSのずれにより、帯域内に
リップルが発生する。また、図１２（ａ）（ｂ）に示す
ように、共振周波数の差Δｆを小さくした場合には、通
過帯域が凸状になるという問題点がある。By the way, the composite surface acoustic wave filter has a drawback that the degree of freedom for changing the bandwidth is small due to its filter principle. That is, it is important to the resonance frequency f rS of the series arm resonator 2S and the anti-resonance frequency f ap of the parallel arm resonator 2P is substantially matched, not substantially match a resonant frequency f rS and the anti-resonance frequency f ap When trying to obtain a filter with a large bandwidth in,
As shown in (b), the difference in resonance frequency Δf ( fr s −
f rP) must be significantly, in this case, the shift of the resonance frequency f rS and anti-resonance frequency f ap, ripple is generated in the band. Further, as shown in FIGS. 12A and 12B, when the resonance frequency difference Δf is reduced, the pass band becomes convex.
【０００８】従って、適正なフィルタ特性を得つつ帯域
幅を変化させるためには、それぞれの共振器２の共振周
波数と反共振周波数との周波数差を変化させなければな
らない。周波数差を変化させる方法としては、例えば、
圧電基板１の電気機械結合係数を変化させる方法があ
る。この方法は、電気機械結合係数が大きくなると、共
振器２の共振周波数と反共振周波数の周波数差は大きく
なり、電気機械結合係数が小さくなれば共振器２の共振
周波数と反共振周波数の周波数差は小さくなることを利
用するものである。従って、帯域幅の大きいフィルタが
必要な場合には、電気機械結合係数の大きい基板を用
い、帯域幅の小さいフィルタが必要な場合には、電気機
械結合係数の小さい基板を用いればよいことになる。Therefore, in order to change the bandwidth while obtaining proper filter characteristics, it is necessary to change the frequency difference between the resonance frequency and the anti-resonance frequency of each resonator 2. As a method of changing the frequency difference, for example,
There is a method of changing the electromechanical coupling coefficient of the piezoelectric substrate 1. In this method, when the electromechanical coupling coefficient increases, the frequency difference between the resonance frequency and the antiresonance frequency of the resonator 2 increases, and when the electromechanical coupling coefficient decreases, the frequency difference between the resonance frequency and the antiresonance frequency of the resonator 2 increases. Takes advantage of the fact that it becomes smaller. Therefore, when a filter having a large bandwidth is required, a substrate having a large electromechanical coupling coefficient is used, and when a filter having a small bandwidth is required, a substrate having a small electromechanical coupling coefficient is used. .
【０００９】[0009]
【発明が解決しようとする課題】しかしながら、用いる
基板を変えることで周波数差を変化させる従来の方法で
は、以下の問題がある。即ち、８００ＭＨｚ以上の高周
波フィルタに用いられる圧電基板としては、３６°Ｙ−
ＸLiTaO3（電気機械結合係数ｋ2 ＝０．０４７）と、６
４°Ｙ−ＸのLiNbO3（電気機械結合係数ｋ2 ＝０．１
１）の２種類しか有用な基板がないため、各通信方法で
要求される周波数帯域幅（３３ＭＨｚ，２５ＭＨｚ，１
７ＭＨｚ等）に十分に対応したフィルタを実現するのは
困難である。However, the conventional method of changing the frequency difference by changing the substrate used has the following problems. That is, as a piezoelectric substrate used for a high frequency filter of 800 MHz or more, 36 ° Y-
XLiTaO 3 (electromechanical coupling coefficient k 2 = 0.047) and 6
4 ° Y-X LiNbO 3 (electromechanical coupling coefficient k 2 = 0.1
Since there are only two types of useful substrates in 1), the frequency bandwidth required by each communication method (33 MHz, 25 MHz, 1
It is difficult to realize a filter sufficiently compatible with 7 MHz).
【００１０】本発明は、上記の事情に鑑み、帯域幅に関
して設計の自由度が高い弾性表面波フィルタを提供する
ことを目的とする。In view of the above circumstances, it is an object of the present invention to provide a surface acoustic wave filter having a high degree of freedom in design with respect to bandwidth.
【００１１】[0011]
【課題を解決するための手段】本発明の弾性表面波フィ
ルタは、圧電基板上に櫛型電極とグレーティング反射器
とから成る共振器を２つ備え、一方の共振器を信号線に
電気的に直列に接続し、他方の共振器を信号線に電気的
に並列に接続して成るフィルタ機能単位を一つ以上備え
た複合型の弾性表面波フィルタにおいて、前記の直列に
接続された共振器及び／又は並列に接続された共振器の
前記櫛型電極が、連続して隣り合う電極指を一組以上有
して成ることを特徴とする。A surface acoustic wave filter according to the present invention comprises two resonators each having a comb-shaped electrode and a grating reflector on a piezoelectric substrate, and one of the resonators is electrically connected to a signal line. A composite-type surface acoustic wave filter comprising one or more filter function units, which are connected in series and the other resonator is electrically connected in parallel to a signal line, wherein the resonator connected in series and And / or the comb-shaped electrodes of the resonators connected in parallel have one or more sets of electrode fingers that are continuously adjacent to each other.
【００１２】[0012]
【作用】連続して隣り合う電極指を備えた櫛型電極は、
当該隣り合う電極指を境に個別の櫛型電極を複数備えた
ものに相当する。複数の櫛型電極を備えた共振器は、そ
の櫛型電極数に応じて共振点と反共振点の周波数が変化
する。即ち、共振器の共振点と反共振点を任意に変え得
ることになる。従って、このような任意の共振点と反共
振点を持つ共振器にてフィルタ機能単位を構成して成る
弾性表面波フィルタであれば、通過帯域幅を任意に設定
することができる。[Function] The comb-shaped electrode including the electrode fingers that are adjacent to each other is
This corresponds to the one provided with a plurality of individual comb-shaped electrodes with the adjacent electrode fingers as boundaries. In a resonator having a plurality of comb electrodes, the frequencies at the resonance point and the antiresonance point change according to the number of the comb electrodes. That is, the resonance point and the anti-resonance point of the resonator can be arbitrarily changed. Therefore, in the surface acoustic wave filter in which the filter function unit is configured by the resonator having such an arbitrary resonance point and anti-resonance point, the pass band width can be set arbitrarily.
【００１３】[0013]
【実施例】以下、本発明をその実施例を示す図に基づい
て説明する。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing its embodiments.
【００１４】図１は、本発明の複合型（ラダー接続型）
の弾性表面波フィルタを示す模式的平面図である。この
弾性表面波フィルタは、６４°Ｙ−Ｘ（ＹカットＸ軸伝
搬）のLiNbO3から成る圧電基板１上に櫛型電極２ａとグ
レーティング反射器２ｂ，２ｂとから成る１ポート共振
器２を２つ備えたものを一つのフィルタ機能単位３とす
るものであり、一方の１ポート共振器２を信号線４に電
気的に直列に接続し（これを直列腕共振器２Ｓとい
う）、他方の１ポート共振器２を信号線に電気的に並列
に接続している（これを並列腕共振器２Ｐという）。そ
して、上記のフィルタ機能単位３を３段に並べて構成さ
れている。FIG. 1 shows a composite type (ladder connection type) of the present invention.
FIG. 3 is a schematic plan view showing the surface acoustic wave filter of FIG. This surface acoustic wave filter has two 1-port resonators 2 each composed of a comb-shaped electrode 2a and grating reflectors 2b and 2b on a piezoelectric substrate 1 made of LiNbO 3 of 64 ° Y-X (Y-cut X-axis propagation). The one provided with one filter function unit 3 has one 1-port resonator 2 electrically connected in series to the signal line 4 (this is referred to as a series arm resonator 2S), and the other 1 The port resonator 2 is electrically connected in parallel to the signal line (this is called a parallel arm resonator 2P). The filter function units 3 are arranged in three stages.
【００１５】また、図１の弾性表面波フィルタは、通過
帯域の中心周波数ｆ0 を９０２．５ＭＨｚとし、帯域幅
が２５ＭＨｚとなるようにしており、直列腕共振器２Ｓ
の櫛型電極２ａの電極指数および並列腕共振器２Ｐの櫛
型電極２ａの電極指数は、それぞれ１２０本とし、直列
腕共振器２Ｓの櫛型電極２ａの電極指の長さ（開口長）
を７０μｍに、並列腕共振器２Ｐの櫛型電極２ａの電極
指の長さ（開口長）を１４０μｍに設定している。In the surface acoustic wave filter of FIG. 1, the center frequency f 0 of the pass band is set to 902.5 MHz and the band width is set to 25 MHz.
The electrode index of the comb-shaped electrode 2a and the electrode index of the comb-shaped electrode 2a of the parallel arm resonator 2P are 120, respectively, and the length (opening length) of the electrode finger of the comb-shaped electrode 2a of the series arm resonator 2S is set.
Is set to 70 μm, and the length (opening length) of the electrode fingers of the comb-shaped electrode 2a of the parallel arm resonator 2P is set to 140 μm.
【００１６】そして、前記の直列腕共振器２Ｓの櫛型電
極２ａには、連続して隣り合う電極指が一組形成されて
いる。The comb-shaped electrode 2a of the series arm resonator 2S is formed with a set of electrode fingers that are adjacent to each other.
【００１７】図２は、図１の弾性表面波フィルタにおけ
る一つの直列腕共振器２Ｓの櫛型電極２ａを拡大して示
す模式的平面図である。この図では、連続して隣り合う
電極指を○で囲んで示している。この直列腕共振器２Ｓ
の櫛型電極２ａの電極指数は、前述したように１２０本
である。そして、上記の連続して隣り合う電極指を境
に、その両側に６０本の電極指がそれぞれ存在するよう
にしてある。FIG. 2 is an enlarged schematic plan view showing a comb-shaped electrode 2a of one series arm resonator 2S in the surface acoustic wave filter shown in FIG. In this figure, the electrode fingers that are adjacent to each other are circled and shown. This series arm resonator 2S
The comb-shaped electrode 2a has an electrode index of 120 as described above. Then, with the above-mentioned consecutively adjacent electrode fingers as boundaries, 60 electrode fingers are present on both sides thereof.
【００１８】図３は、図２と同様、直列腕共振器２Ｓの
櫛型電極２ａを拡大して示す模式的平面図であって櫛型
電極２ａの変形例を示した図である。この図３の櫛型電
極２ａには、連続して隣り合う電極指が二組形成されて
いる。この図３の櫛型電極２ａの電極指数は、前述した
ように１２０本であり、上記の連続して隣り合う電極指
を境に、その両側に４０本の電極指がそれぞれ存在する
ようにしてある。Similar to FIG. 2, FIG. 3 is an enlarged schematic plan view showing the comb-shaped electrode 2a of the series arm resonator 2S, showing a modification of the comb-shaped electrode 2a. In the comb-shaped electrode 2a of FIG. 3, two pairs of electrode fingers that are adjacent to each other are formed continuously. The electrode index of the comb-shaped electrode 2a in FIG. 3 is 120 as described above, and 40 electrode fingers are present on both sides of the electrode finger, which is adjacent to each other, as a boundary. is there.
【００１９】図４も、図２と同様、直列腕共振器２Ｓの
櫛型電極２ａを拡大して示す模式的平面図であって櫛型
電極２ａの変形例を示した図である。この図４の櫛型電
極２ａには、連続して隣り合う電極指が三組形成されて
いる。この図４の櫛型電極２ａの電極指数は、前述した
ように１２０本であり、上記の連続して隣り合う電極指
を境に、その両側に３０本の電極指がそれぞれ存在する
ようにしてある。Similar to FIG. 2, FIG. 4 is also a schematic plan view showing an enlarged comb-shaped electrode 2a of the series arm resonator 2S, showing a modification of the comb-shaped electrode 2a. In the comb-shaped electrode 2a of FIG. 4, three pairs of electrode fingers that are adjacent to each other are formed. The comb-shaped electrode 2a in FIG. 4 has an electrode index of 120 as described above, and 30 electrode fingers are present on both sides of the electrode finger, which is adjacent to each other, as a boundary. is there.
【００２０】図５も、図２と同様、直列腕共振器２Ｓの
櫛型電極２ａを拡大して示す模式的平面図であって櫛型
電極２ａの変形例を示した図である。この図４の櫛型電
極２ａには、連続して隣り合う電極指が二組形成されて
いるが、そのうちの一組の連続して隣り合う電極指は、
櫛型電極２ａを構成する一方の電極側に形成され、他の
一組の連続して隣り合う電極指は、櫛型電極２ａを構成
する他方の電極側に形成されている。そして、上記二組
の連続して隣り合う電極指の形成位置が互いに重ならな
いようにしてある。Similar to FIG. 2, FIG. 5 is also an enlarged schematic plan view showing the comb-shaped electrode 2a of the series arm resonator 2S, showing a modification of the comb-shaped electrode 2a. In the comb-shaped electrode 2a of FIG. 4, two sets of electrode fingers that are continuously adjacent to each other are formed.
The pair of electrode fingers that are formed on one electrode side that configures the comb-shaped electrode 2a and that are adjacent to each other are formed on the other electrode side that configures the comb-shaped electrode 2a. Further, the formation positions of the two pairs of the electrode fingers that are adjacent to each other are not overlapped with each other.
【００２１】上述した図２乃至図５のごとく、連続して
隣り合う電極指を備えた櫛型電極２ａは、当該隣り合う
電極指を境に個別の櫛型電極を複数備えたものに相当す
る。即ち、図２の場合は２分割された櫛型電極となり、
図３及び図５の場合は３分割された櫛型電極となり、図
４の場合は４分割された櫛型電極となる。そして、この
ように複数の櫛型電極（分割された櫛型電極）を備えた
共振器は、その櫛型電極数（分割数）に応じて共振点と
反共振点の周波数が変化する。As shown in FIG. 2 to FIG. 5 described above, the comb-shaped electrode 2a provided with the electrode fingers which are adjacent to each other corresponds to the one provided with a plurality of individual comb-shaped electrodes with the adjacent electrode fingers as boundaries. . That is, in the case of FIG. 2, the comb-shaped electrode is divided into two,
3 and 5, the comb-shaped electrode is divided into three parts, and in the case of FIG. 4, the comb-shaped electrode is divided into four parts. In the resonator including the plurality of comb-shaped electrodes (divided comb-shaped electrodes), the frequencies at the resonance point and the anti-resonance point change according to the number of comb-shaped electrodes (the number of divisions).
【００２２】図６は、共振器２における周波数−減衰量
特性を示したグラフであり、前記の図２の構成の櫛型電
極（図では、２分割として細線で表記している）、前記
図３の構成の櫛型電極（図では、３分割として太線で表
記している）、及び、従来の櫛型電極（図では、正規型
として点線で表記している）の３つの構成について示し
ている。FIG. 6 is a graph showing the frequency-attenuation amount characteristic in the resonator 2, wherein the comb-shaped electrode having the structure shown in FIG. The three configurations of the comb-shaped electrode having the configuration of 3 (indicated by thick lines in the figure as three divisions) and the conventional comb-shaped electrode (indicated by dotted lines as the normal type in the figure) are shown. There is.
【００２３】上記の図６から明らかなように、２分割さ
れた櫛型電極を有する共振器における最も高い減衰点
（反共振点）と共振点との間隔は、正規型電極を有する
共振器の反共振点と共振点との間隔よりも７ＭＨｚ狭ま
っている。また、３分割された櫛型電極を有する共振器
の反共振点と共振点との間隔は、正規型電極を有する共
振器の反共振点と共振点との間隔よりも１１ＭＨｚ狭ま
っている。As is apparent from FIG. 6 described above, the interval between the highest attenuation point (anti-resonance point) and the resonance point in the resonator having the comb-shaped electrode divided into two is the same as that of the resonator having the normal type electrode. It is narrower than the distance between the anti-resonance point and the resonance point by 7 MHz. Further, the interval between the anti-resonance point and the resonance point of the resonator having the comb-shaped electrodes divided into three parts is 11 MHz narrower than the interval between the anti-resonance point and the resonance point of the resonator having the normal type electrode.
【００２４】即ち、分割された櫛型電極２ａを有する共
振器２は、その分割数によって共振器２の共振点と反共
振点を任意に変え得ることになる。従って、このような
任意の共振点と反共振点を持つ共振器にてフィルタ機能
単位を構成して成る本発明の弾性表面波フィルタであれ
ば、通過帯域幅を任意に設定することができる。That is, in the resonator 2 having the divided comb-shaped electrodes 2a, the resonance point and the anti-resonance point of the resonator 2 can be arbitrarily changed depending on the number of divisions. Therefore, in the surface acoustic wave filter of the present invention in which the filter function unit is configured by the resonator having such an arbitrary resonance point and anti-resonance point, the pass band width can be set arbitrarily.
【００２５】図７は、図１に示した弾性表面波フィルタ
における周波数−減衰量特性を示したグラフである。な
お、比較のため、図８に示した従来の弾性表面波フィル
タにおける周波数−減衰量特性も併記している。この図
７から明らかなように、本発明の弾性表面波フィルタで
あれば、通過帯域幅が２５ＭＨｚとなるように周波数特
性を設定できるとともに、たとえこのように狭帯域化さ
せたとしても、従来例で示した図１２のように、共振周
波数の差Δｆを小さくした場合に通過帯域が凸状になる
ということもない。また、圧電基板の材質変更だけでは
各通信方法で要求される周波数帯域幅（３３ＭＨｚ，２
５ＭＨｚ，１７ＭＨｚ）に十分に対応できないといった
問題も解消することができる。FIG. 7 is a graph showing the frequency-attenuation amount characteristic of the surface acoustic wave filter shown in FIG. For comparison, the frequency-attenuation characteristic of the conventional surface acoustic wave filter shown in FIG. 8 is also shown. As is clear from FIG. 7, in the surface acoustic wave filter of the present invention, the frequency characteristic can be set so that the pass band width is 25 MHz, and even if the band is narrowed in this way, the conventional example As shown in FIG. 12, the pass band does not become convex when the resonance frequency difference Δf is reduced. Also, the frequency bandwidth (33 MHz, 2 MHz) required by each communication method can be obtained only by changing the material of the piezoelectric substrate.
It is also possible to solve the problem that it cannot fully support 5 MHz and 17 MHz).
【００２６】なお、以上の実施例では、連続して隣り合
う電極指により分割された櫛型電極の電極指数が同数と
なるようにしたが、このように同数とすることに限られ
ないことは勿論であり、分割された櫛型電極の電極指数
が異なるときでも、上記実施例と同様の作用を発揮する
ことができるものである。また、直列腕共振器２Ｓにお
いて櫛型電極を分割するようにしたが、並列腕共振器２
Ｐにおいて連続して隣り合う電極指により櫛型電極を分
割してもよい。更に、８００ＭＨｚ帯の仕様に限らず、
どのような周波数帯においても本発明の複合型の弾性表
面波フィルタは前述した作用を発揮し得るものである。In the above embodiment, the comb-shaped electrodes divided by the electrode fingers which are adjacent to each other have the same index, but the number of comb-shaped electrodes is not limited to the same. Of course, even when the divided comb-shaped electrodes have different electrode indices, the same action as in the above-described embodiment can be exhibited. Further, although the comb-shaped electrodes are divided in the series arm resonator 2S, the parallel arm resonator 2 is divided.
The comb-shaped electrodes may be divided by electrode fingers that are adjacent to each other in P. Furthermore, it is not limited to the specifications of 800 MHz band,
The composite type surface acoustic wave filter of the present invention can exhibit the above-mentioned operation in any frequency band.
【００２７】[0027]
【発明の効果】以上のように、本発明によれば、直列腕
共振器及び／又は並列腕共振器の共振周波数と反共振周
波数との周波数差を変化させることができるので、単に
共振周波数と反共振周波数とを略一致させないでフィル
タを得ようとする場合の欠点を解消できる。また、圧電
基板の材質変更で各通信方法で要求される周波数帯域幅
を得ようとするときの不十分さも解消できるという効果
を奏する。As described above, according to the present invention, since the frequency difference between the resonance frequency and the anti-resonance frequency of the series arm resonator and / or the parallel arm resonator can be changed, it is possible to simply change the resonance frequency. It is possible to eliminate the drawbacks when trying to obtain a filter without causing the anti-resonance frequency to substantially match. In addition, it is possible to eliminate the insufficiency in trying to obtain the frequency bandwidth required by each communication method by changing the material of the piezoelectric substrate.
【図１】本発明の複合型の弾性表面波フィルタを示す模
式的平面図である。FIG. 1 is a schematic plan view showing a composite surface acoustic wave filter of the present invention.
【図２】図１の弾性表面波フィルタの直列腕共振器を拡
大して示す模式的平面図である。FIG. 2 is an enlarged schematic plan view showing a series arm resonator of the surface acoustic wave filter of FIG.
【図３】本発明の共振器の変形例（３分割）を示す模式
的平面図である。FIG. 3 is a schematic plan view showing a modified example (divided into three parts) of the resonator of the present invention.
【図４】本発明の共振器の変形例（４分割）を示す模式
的平面図である。FIG. 4 is a schematic plan view showing a modified example (four divisions) of the resonator of the present invention.
【図５】本発明の共振器の変形例（３分割）を示す模式
的平面図である。FIG. 5 is a schematic plan view showing a modified example (divided into three parts) of the resonator of the present invention.
【図６】本発明の共振器（分割型）および従来の共振器
（正規型）における周波数−減衰量特性を示したグラフ
である。FIG. 6 is a graph showing frequency-attenuation amount characteristics of a resonator of the present invention (divided type) and a conventional resonator (normal type).
【図７】本発明の弾性表面波フィルタおよび従来の弾性
表面波フィルタにおける周波数−減衰量特性を示したグ
ラフである。FIG. 7 is a graph showing frequency-attenuation amount characteristics of the surface acoustic wave filter of the present invention and the conventional surface acoustic wave filter.
【図８】従来の複合型の弾性表面波フィルタを示す模式
的平面図である。FIG. 8 is a schematic plan view showing a conventional composite type surface acoustic wave filter.
【図９】フィルタ機能単位を示す模式的平面図である。FIG. 9 is a schematic plan view showing a filter function unit.
【図１０】同図（ａ）は直列腕共振器及び並列腕共振器
の周波数−インピーダンス特性を示し、同図（ｂ）は同
図（ａ）の両共振器を用いた場合の周波数−減衰量特性
を示したグラフである。10 (a) shows frequency-impedance characteristics of a series arm resonator and a parallel arm resonator, and FIG. 10 (b) shows frequency-attenuation when both resonators of FIG. 10 (a) are used. It is the graph which showed the quantity characteristic.
【図１１】同図（ａ）は直列腕共振器及び並列腕共振器
の周波数−インピーダンス特性を示し、同図（ｂ）は同
図（ａ）の両共振器を用いた場合の周波数−減衰量特性
を示したグラフである。11A shows frequency-impedance characteristics of a series arm resonator and a parallel arm resonator, and FIG. 11B shows frequency-attenuation when both resonators of FIG. 11A are used. It is the graph which showed the quantity characteristic.
【図１２】同図（ａ）は直列腕共振器及び並列腕共振器
の周波数−インピーダンス特性を示し、同図（ｂ）は同
図（ａ）の両共振器を用いた場合の周波数−減衰量特性
を示したグラフである。FIG. 12 (a) shows frequency-impedance characteristics of a series arm resonator and a parallel arm resonator, and FIG. 12 (b) shows frequency-attenuation when both resonators of FIG. 12 (a) are used. It is the graph which showed the quantity characteristic.
１ 圧電基板 ２ 共振器 ２Ｓ 直列腕共振器 ２Ｐ 並列腕共振器 ２ａ 櫛型電極 ２ｂ グレーティング反射器 ３ フィルタ機能単位 ４ 信号線 1 Piezoelectric Substrate 2 Resonator 2S Series Arm Resonator 2P Parallel Arm Resonator 2a Comb Electrode 2b Grating Reflector 3 Filter Function Unit 4 Signal Line
───────────────────────────────────────────────────── フロントページの続き (72)発明者 竹内 孝介 大阪府守口市京阪本通２丁目５番５号 三 洋電機株式会社内 (72)発明者 柴田 賢一 大阪府守口市京阪本通２丁目５番５号 三 洋電機株式会社内 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Kosuke Takeuchi 2-5-5 Keihan Hondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Kenichi Shibata 2-chome, Keihan Hondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd.
Claims (1)
反射器とから成る共振器を２つ備え、一方の共振器を信
号線に電気的に直列に接続し、他方の共振器を信号線に
電気的に並列に接続して成るフィルタ機能単位を一つ以
上備えた複合型の弾性表面波フィルタにおいて、前記の
直列に接続された共振器及び／又は並列に接続された共
振器の前記櫛型電極が、連続して隣り合う電極指を一組
以上有して成ることを特徴とする弾性表面波フィルタ。1. A piezoelectric substrate is provided with two resonators each including a comb-shaped electrode and a grating reflector, one resonator is electrically connected in series to a signal line, and the other resonator is connected to a signal line. A composite type surface acoustic wave filter comprising one or more filter functional units electrically connected in parallel, wherein the resonators connected in series and / or the resonators connected in parallel are comb-shaped. A surface acoustic wave filter, characterized in that the electrode has one or more sets of electrode fingers that are continuously adjacent to each other.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12993995A JP3459494B2 (en) | 1995-05-29 | 1995-05-29 | Surface acoustic wave filter |
| DE69636897T DE69636897T2 (en) | 1995-05-29 | 1996-05-28 | Acoustic surface wave filter |
| EP96108469A EP0746095B1 (en) | 1995-05-29 | 1996-05-28 | Surface acoustic wave filter |
| US08/654,608 US5844453A (en) | 1995-05-29 | 1996-05-29 | Surface acoustic wave filter utilizing a transducer having interdigital electrodes and continuously adjacent electrodes |
| US09/158,071 US6034577A (en) | 1995-05-29 | 1998-09-22 | Integrated interdigital electrode saw filter with specified distances between input/output electrodes |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12993995A JP3459494B2 (en) | 1995-05-29 | 1995-05-29 | Surface acoustic wave filter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08330897A true JPH08330897A (en) | 1996-12-13 |
| JP3459494B2 JP3459494B2 (en) | 2003-10-20 |
Family
ID=15022176
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12993995A Expired - Fee Related JP3459494B2 (en) | 1995-05-29 | 1995-05-29 | Surface acoustic wave filter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3459494B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2018199070A1 (en) * | 2017-04-28 | 2018-11-01 | 株式会社村田製作所 | Acoustic wave device, filter and composite filter device |
| JP2022075959A (en) * | 2018-08-13 | 2022-05-18 | 株式会社村田製作所 | Acoustic wave filter |
-
1995
- 1995-05-29 JP JP12993995A patent/JP3459494B2/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2018199070A1 (en) * | 2017-04-28 | 2018-11-01 | 株式会社村田製作所 | Acoustic wave device, filter and composite filter device |
| CN110582937A (en) * | 2017-04-28 | 2019-12-17 | 株式会社村田制作所 | Elastic wave device, filter, and composite filter device |
| US11165409B2 (en) | 2017-04-28 | 2021-11-02 | Murata Manufacturing Co., Ltd. | Acoustic wave device, filter, and composite filter device |
| CN110582937B (en) * | 2017-04-28 | 2023-08-25 | 株式会社村田制作所 | Elastic wave device, filter, and composite filter device |
| JP2022075959A (en) * | 2018-08-13 | 2022-05-18 | 株式会社村田製作所 | Acoustic wave filter |
| US11929737B2 (en) | 2018-08-13 | 2024-03-12 | Murata Manufacturing Co., Ltd. | Acoustic wave filter |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3459494B2 (en) | 2003-10-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0746095B1 (en) | Surface acoustic wave filter | |
| JP3243976B2 (en) | Surface acoustic wave filter | |
| US5543757A (en) | Surface acoustic wave filter including alternate open and shorted reflector grating | |
| JPH11340783A (en) | Surface acoustic wave filter | |
| JP2000261288A (en) | Surface acoustic wave filter, duplexer, and communication device | |
| JPH11312951A (en) | Surface acoustic wave filter | |
| US5760664A (en) | Acoustic wave filter with double reflective gratings and method for producing the same | |
| JP3204112B2 (en) | Surface acoustic wave resonator filter | |
| JPH09181566A (en) | Surface acoustic wave resonator filtering device | |
| JP3459494B2 (en) | Surface acoustic wave filter | |
| JP3890667B2 (en) | Vertically coupled double mode SAW filter | |
| JP4138093B2 (en) | Vertically coupled double mode SAW filter | |
| JP3923283B2 (en) | Surface acoustic wave device | |
| JPH09135145A (en) | Surface acoustic wave filter | |
| JPH0786871A (en) | Surface acoustic wave high frequency filter | |
| JP3117021B2 (en) | Surface acoustic wave filter | |
| JP4004042B2 (en) | Duplexer | |
| JPH06291600A (en) | Surface acoustic wave filter | |
| JPH07176979A (en) | Surface acoustic wave filter | |
| JPH08321743A (en) | Surface acoustic wave filter | |
| JPH1079641A (en) | Surface acoustic wave filter | |
| JPH11112284A (en) | Surface acoustic wave filter | |
| JPH10270981A (en) | Surface acoustic wave filter | |
| JP3462536B2 (en) | Surface acoustic wave high frequency filter | |
| JPH10145183A (en) | Surface acoustic wave filter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20070808 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080808 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090808 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100808 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Year of fee payment: 7 Free format text: PAYMENT UNTIL: 20100808 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110808 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Year of fee payment: 8 Free format text: PAYMENT UNTIL: 20110808 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Year of fee payment: 9 Free format text: PAYMENT UNTIL: 20120808 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130808 Year of fee payment: 10 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Year of fee payment: 10 Free format text: PAYMENT UNTIL: 20130808 |
|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313113 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130808 Year of fee payment: 10 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| LAPS | Cancellation because of no payment of annual fees |