JPH03234109A - Ladder filter - Google Patents
Ladder filterInfo
- Publication number
- JPH03234109A JPH03234109A JP2987190A JP2987190A JPH03234109A JP H03234109 A JPH03234109 A JP H03234109A JP 2987190 A JP2987190 A JP 2987190A JP 2987190 A JP2987190 A JP 2987190A JP H03234109 A JPH03234109 A JP H03234109A
- Authority
- JP
- Japan
- Prior art keywords
- series
- resonators
- resonator
- parallel
- high voltage
- 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
Links
- 230000010287 polarization Effects 0.000 claims abstract description 35
- 230000005616 pyroelectricity Effects 0.000 abstract description 15
- 230000000694 effects Effects 0.000 abstract description 12
- 230000002411 adverse Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- 239000000919 ceramic Substances 0.000 description 3
- 238000005476 soldering Methods 0.000 description 3
- 230000002457 bidirectional effect Effects 0.000 description 2
- 229910000679 solder Inorganic materials 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
Landscapes
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野］
本発明は、複数個の直列共振子と並列共振子とを用いて
構成されたラダー型フィルタの改良に関し、特に、圧電
板で構成された各共振子の分極方向が改良されたラダー
型フィルタに関する。[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an improvement of a ladder type filter constructed using a plurality of series resonators and a plurality of parallel resonators, and in particular, to a ladder filter constructed using a plurality of series resonators and parallel resonators. This invention relates to a ladder type filter in which the polarization direction of each resonator is improved.
第２図に、公知のラダー型フィルタの一例を示す、この
ラダー型フィルタでは、４個の直列共振子１〜４が入出
力端間に直列に接続されており、それによって直列腕が
構成されている。他方、各直列共振子１〜４間には、基
準電位との間に、それぞれ、並列共振子５〜７が接続さ
れており、３個の並列腕が構成されている。FIG. 2 shows an example of a known ladder type filter. In this ladder type filter, four series resonators 1 to 4 are connected in series between input and output terminals, thereby forming a series arm. ing. On the other hand, parallel resonators 5 to 7 are connected between each of the series resonators 1 to 4 and a reference potential, forming three parallel arms.
ところで、直列共振子１〜４及び並列共振子５〜７を構
成するための共振子としては、圧電板、例えば圧電セラ
ミック板を厚み方向に分極処理し、かつ該圧電板の両生
面に電極を形成したものを用いることが多い、なお、第
２図の回路構成では、４個の直列共振子１〜４と３個の
並列共振子５〜７が用いられているが、目的とするフィ
ルタ特性に応して、種々の段数のラダー型フィルタが構
成され、使用されている。By the way, as the resonators for configuring the series resonators 1 to 4 and the parallel resonators 5 to 7, a piezoelectric plate, for example, a piezoelectric ceramic plate is polarized in the thickness direction, and electrodes are provided on the bidirectional surfaces of the piezoelectric plate. In addition, in the circuit configuration shown in Fig. 2, four series resonators 1 to 4 and three parallel resonators 5 to 7 are used, but the desired filter characteristics Ladder type filters with various numbers of stages are constructed and used depending on the situation.
ところで、第２図のラダー型フィルタにおいて直列共振
子１〜４及び並列共振子５〜７を構成する各共振子の圧
電板の分極方向については、余り考慮されていないのが
実情であり、僅かに特開昭６３−２１２２１２号に、直
列共振子の圧電板の分極方向を一定方向に揃えた構成が
開示されているに過ぎない。Incidentally, in the ladder type filter shown in Fig. 2, the polarization direction of the piezoelectric plates of each resonator constituting the series resonators 1 to 4 and the parallel resonators 5 to 7 is not really considered. Japanese Patent Laid-Open No. 63-212212 merely discloses a structure in which the polarization directions of the piezoelectric plates of a series resonator are aligned in a fixed direction.
その結果、実際には、第２図の矢印Ｐ１〜Ｐ。As a result, the arrows P1-P in FIG.
で示すように、直列共振子１〜４の圧電板の分極方向が
同一であり、並列共振子５〜７の分極方向が図示のよう
になっている製品も生していた。他方、圧電仮に温度変
化が与えられると、圧電板の焦電性により高電圧が誘起
される。従って、各共振子の分極方向Ｐ１〜Ｐ、が第２
図のような向きの場合に゛は、各共振子１〜７を構成し
ている圧電板の焦電性により誘起される高電圧が、入出
力端子と基準電位との間に相乗的に加わるおそれがあよ
って、はんだ付は等の急激な温度変化が与えられた場合
、焦電性により誘起される高電圧が、入出力端に接続さ
れる能動素子に悪影響を与えるおそれがあった。特に、
接続される能動素子の耐電圧が低い場合には、能動素子
が破壊されることさえあった。As shown in the figure, there were also products in which the polarization directions of the piezoelectric plates of the series resonators 1 to 4 were the same, and the polarization directions of the parallel resonators 5 to 7 were as shown in the figure. On the other hand, if a temperature change is applied to a piezoelectric plate, a high voltage will be induced due to the pyroelectricity of the piezoelectric plate. Therefore, the polarization directions P1 to P of each resonator are the second
In the case of the orientation shown in the figure, the high voltage induced by the pyroelectricity of the piezoelectric plates composing each resonator 1 to 7 is synergistically applied between the input/output terminal and the reference potential. If this occurs and a sudden temperature change is applied, such as during soldering, the high voltage induced by the pyroelectricity may have an adverse effect on the active elements connected to the input/output terminals. especially,
If the withstand voltage of the connected active element is low, the active element may even be destroyed.
よって、本発明の目的は、圧電板の焦電性に起因する、
入出力端に接続される素子への悪影響を効果的に防止し
得る構成を備えたラダー型フィルタを提供することにあ
る。Therefore, the object of the present invention is to reduce the
It is an object of the present invention to provide a ladder filter having a configuration that can effectively prevent adverse effects on elements connected to input and output terminals.
本発明は、複数個の直列共振子で構成された直列腕と、
並列共振子で構成された並列腕とを有し、各共振子が圧
電板を用いて構成されているラダー型フィルタにおいて
、下記の構成を備えることを特徴とする。The present invention includes a series arm composed of a plurality of series resonators,
A ladder type filter having parallel arms each composed of parallel resonators, each of which is composed of a piezoelectric plate, is characterized by having the following configuration.
すなわち、直列腕の少なくとも一方の端部に配置された
直列共振子及び該直列共振子に接続された並列共振子の
圧電板の分極方向が、直列腕の少なくとも一方の端部に
配置された直列共振子と該直列共振子に接続された並列
共振子との接続点側から見て同一方向とされていること
を特徴とする。That is, the polarization directions of the piezoelectric plates of the series resonator disposed at at least one end of the series arm and the parallel resonator connected to the series resonator are different from those of the series resonator disposed at at least one end of the series arm. The resonator and the parallel resonator connected to the series resonator are oriented in the same direction when viewed from the connection point side.
好ましくは、直列共振子の圧電板の分極方向は、直列腕
に沿って交互に逆方向とされる。Preferably, the polarization directions of the piezoelectric plates of the series resonators are alternately opposite along the series arms.
直列腕の少なくとも一方の端部、すなわち入力端側また
は出力端側の直列共振子の圧電板の分極方向と、この直
列共振子に接続された並列共振子の圧電板の分極方向と
が上記のように設定されているため、該直列共振子と並
列共振子との接続点において、焦電性に起因する高電圧
が相殺され、入力端または出力端への高電圧の印加が効
果的に防止される。The polarization direction of the piezoelectric plate of the series resonator at at least one end of the series arm, that is, the input end side or the output end side, and the polarization direction of the piezoelectric plate of the parallel resonator connected to this series resonator are as described above. Because of this setting, the high voltage caused by pyroelectricity is canceled out at the connection point between the series resonator and the parallel resonator, effectively preventing the application of high voltage to the input end or output end. be done.
また、直列腕を構成している複数個の直列共振子の圧電
板の分極方向を交互に逆極性にした場合、直列共振子に
おいて焦電性に起因して発生した高電圧が、隣接する直
列共振子間で相殺されることになるため、焦電性に起因
する高電圧が相乗的に入出力端に加わることがより一層
効果的に防止される。Furthermore, if the polarization directions of the piezoelectric plates of the plurality of series resonators constituting the series arm are alternately reversed, the high voltage generated due to pyroelectricity in the series resonators will be transferred to the adjacent series resonators. Since the resonators cancel each other out, high voltage caused by pyroelectricity is more effectively prevented from being applied synergistically to the input and output terminals.
第１図に、本発明の一実施例が適用されたラダー型フィ
ルタを示す。このラダー型フィルタでは、ｎ個の直列共
振子Ｘ、〜Ｘいが入出力端間に直列に接続されて直列腕
が構成されている。他方、直列共振子Ｘ１〜Ｘ１間に、
それぞれ、並列共振子Ｙ Ｉ””’ Ｙ −＋が接続さ
れて、それぞれ並列腕を構成している。FIG. 1 shows a ladder type filter to which an embodiment of the present invention is applied. In this ladder type filter, n series resonators X, -Xi are connected in series between input and output terminals to form a series arm. On the other hand, between the series resonators X1 and X1,
Parallel resonators Y I""' Y -+ are connected to each of them to form a parallel arm.
本実施例のラダー型フィルタの第１の特徴は、直列腕の
両端に配置された直列共振子Ｘ、、Ｘ、。The first feature of the ladder filter of this embodiment is the series resonators X, , X, arranged at both ends of the series arms.
と、該直列共振子ＸＩ、Ｘ−に接続された並列共振子Ｙ
ｌ、Ｙ−＋ との接続点Ａ、Ｂから見て、それぞれ、直
列共振子ｘｌ及び並列共振子Ｙ１の圧電板の分極方向Ｐ
８□ ＰＦ＋、並びに直列共振子Ｘ５及び並列共振子Ｙ
１−１の圧電板の分極方向Ｐ ｌｌｌ１＋Ｐア。、、１
．が同一方向とされていることにある。and the series resonator XI, the parallel resonator Y connected to X-
The polarization direction P of the piezoelectric plates of the series resonator xl and the parallel resonator Y1, respectively, as seen from the connection points A and B with
8□ PF+, and series resonator X5 and parallel resonator Y
Polarization direction of piezoelectric plate 1-1 Pll1+Pa. ,,1
．． are assumed to be in the same direction.
また、本実施例のラダー型フィルタの第２の特徴は、直
列共振子Ｘ１〜Ｘ、の圧電板の分極方向Ｐ ＸＩ＋
Ｐ Ｘ＊’−−’−””＋ Ｐ １１１１が、直列腕
に沿って交互に逆方向とされていることにある。The second feature of the ladder filter of this embodiment is that the polarization direction P XI+ of the piezoelectric plates of the series resonators X1 to X is
P
次に、上記実施例のラダー型フィルタの作用を説明する
。Next, the operation of the ladder type filter of the above embodiment will be explained.
今、ラダー型フィルタにはんだ付は等によりゑ、激な温
度変化が与えられた場合を仮定する。この場合、接続点
Ａに着目すると、直列共振子Ｘ１及び並列共振子Ｙ１の
圧電板の分極方向Ｐ、、、Ｐア。Now, let us assume that a ladder type filter is subjected to drastic temperature changes due to soldering. In this case, if we pay attention to the connection point A, the polarization directions P, .
が上記のように設定されているため、直列共振子χ１及
び並列共振子Ｙ、の圧電板の焦電性に起因する高電圧は
接続点Ａに対して逆極性で加わることになるため相殺さ
れ、該焦電性に起因する高電圧が入力端と基準電位との
間に印加されることが効果的に防止される。is set as above, the high voltage caused by the pyroelectricity of the piezoelectric plates of the series resonator χ1 and the parallel resonator Y is applied to the connection point A with opposite polarity, so it is canceled out. , high voltage caused by the pyroelectricity is effectively prevented from being applied between the input terminal and the reference potential.
出力端側においても、接続点Ｂに対して、直列共振子Ｘ
。及び並列共振子Ｙ、−１の圧電板の焦電性に起因する
高電圧が、同様にして相殺され、両正電板の焦電性に起
因する高電圧の出力端側への印加が効″果的に防止され
る。Also on the output end side, the series resonator X is connected to the connection point B.
. The high voltage caused by the pyroelectricity of the piezoelectric plates of parallel resonators Y and -1 are canceled out in the same way, and the high voltage caused by the pyroelectricity of both positive electric plates is effectively applied to the output end side. ``Effectively prevented.
さらに、本実施例のラダー型フィルタでは、直列腕を構
成してるｎ個の直列共振子Ｘ１〜Ｘ１の圧電板の分極方
向は、図示の矢印Ｐ、、、ＰＸ□Ｐｘ、、で示すように
直列腕に沿って交互に逆方向とされているため、直列共
振子Ｘ１〜Ｘ、、の圧電板の焦電性に起因する高電圧が
隣接する直列共振子間で相殺される。よって、ｎ個の直
列共振子Ｘ、〜Ｘ、に起因する入出力端への高電圧の印
加も防止することができる。Furthermore, in the ladder type filter of this embodiment, the polarization directions of the piezoelectric plates of the n series resonators X1 to X1 constituting the series arm are as shown by the arrows P, , PX□Px, in the figure. Since the directions are alternately opposite along the series arms, high voltages caused by the pyroelectricity of the piezoelectric plates of the series resonators X1 to X, , are canceled out between adjacent series resonators. Therefore, it is also possible to prevent the application of high voltage to the input/output terminals due to the n series resonators X, .about.X.
よって、入力端あるいは出力端に接続される能動素子等
の他の素子への悪影響を効果的に防止し得ることがわか
る。Therefore, it can be seen that adverse effects on other elements such as active elements connected to the input end or the output end can be effectively prevented.
なお、第１図に示した実施例では、接続点Ａ及びＢの双
方において、本発明の分極方向条件を満たすように構成
したが、何れが一方の接続点ＡまたはＢ側においてのみ
本発明の分極方向についての条件を満たすように構成し
てもよい０例えば、直列共振子Ｘ７と並列共振子ＹＭ−
１の圧電板の分極方向を上記のように設定さえすれば、
接続点Ａ側では第１図実施例のように分極方向が設定さ
れていすとも、入力端側はともがく、出力端側に接続さ
れる素子への悪影響は一応防止し得るがらである。In the embodiment shown in FIG. 1, both connection points A and B are configured to satisfy the polarization direction conditions of the present invention, but only one connection point A or B side is configured to satisfy the polarization direction condition of the present invention. For example, a series resonator X7 and a parallel resonator YM-
As long as the polarization direction of piezoelectric plate 1 is set as above,
Even if the polarization direction is set on the connection point A side as in the embodiment shown in FIG. 1, the input end side will struggle, although an adverse effect on the elements connected to the output end side can be prevented for the time being.
また、直列共振子Ｘ１〜Ｘ７の圧電板の分極方向を直列
腕に沿って交互に逆極性とする必要も必ずしもない。す
なわち、接続点Ａまたは接続点Ｂにおける分極方向の条
件を上記のように設定さえすれは一応の効果を得ること
ができるからである。Furthermore, it is not necessarily necessary that the polarization directions of the piezoelectric plates of the series resonators X1 to X7 are alternately reversed along the series arms. That is, as long as the polarization direction conditions at connection point A or connection point B are set as described above, a certain effect can be obtained.
さらに、本発明が適用されるラダー型フィルタは°、第
１図に示したように、ｎ個の直列共振子と（ｎ−１）個
の並列共振子とを有するものに限らない、第３図に示す
ように偶数個の共振子を用いたラダー型フィルタにも本
発明を適用することができる。Further, the ladder type filter to which the present invention is applied is not limited to the one having n series resonators and (n-1) parallel resonators as shown in FIG. As shown in the figure, the present invention can also be applied to a ladder type filter using an even number of resonators.
第３図のラダー型フィルタでは、２個の直列共振子１１
．１２と２個の並列共振子１３．１４とがラダー型に結
線されている。そして、直列共振子１１と並列共振子１
３との接続点Ｃから見て、直列共振子１１及び並列共振
子１３の圧電板の分極方向Ｐ Ｉｌ、 Ｐ １３が同
一方向とされているため、入力端側において、焦電性に
起因する高電圧が印加されることが効果的に防止される
。In the ladder type filter shown in FIG. 3, two series resonators 11
．． 12 and two parallel resonators 13 and 14 are connected in a ladder shape. Then, the series resonator 11 and the parallel resonator 1
Since the polarization directions P Il and P 13 of the piezoelectric plates of the series resonator 11 and the parallel resonator 13 are in the same direction when viewed from the connection point C with High voltages are effectively prevented from being applied.
また、直列共振子１１．１２の圧電板の分極方向が図示
の矢印の方向に示すように逆方向とされているため、直
列共振子１１．１２の圧電板の焦電性による高電圧も効
果的に相殺される。従って、出力端側には、僅かに並列
共振子１４の圧電板の焦電性に起因する電圧が印加され
るだけであるため、出力端側に接続される素子への悪影
響も低減される。In addition, since the polarization direction of the piezoelectric plates of the series resonators 11 and 12 is opposite as shown in the direction of the arrow in the figure, the high voltage due to the pyroelectricity of the piezoelectric plates of the series resonators 11 and 12 is also effective. are canceled out. Therefore, since only a slight voltage due to the pyroelectricity of the piezoelectric plate of the parallel resonator 14 is applied to the output end, the adverse effect on the elements connected to the output end is also reduced.
上記のように、偶数個の共振子を用いたラダー型フィル
タにも、本発明を適用することにより、ラダー型フィル
タに接続される能動素子等への悪影響を効果的に防止し
得ることがわかる。As described above, it can be seen that by applying the present invention to a ladder type filter using an even number of resonators, it is possible to effectively prevent adverse effects on active elements etc. connected to the ladder type filter. .
次に、具体的な実験結果につき説明する。第１図に示し
たラダー型フィルタにおいて、ｎ＝４とした場合、すな
わち第２図に示したラダー型フィルタと同様に７個の共
振子を用いてラダー型フィルタを構成した。このラダー
型フィルタを複数個用意し、２６０°Ｃの温度の溶融は
んだに３秒間浸漬し、次に溶融はんだから引き上げた後
１ｏ分経過した状態で、入力端とアース電位間の電圧を
測定した。なお、測定に際しては、入力インピーダンス
はＩＭΩ／ １０ ｐ Ｆとした。Next, specific experimental results will be explained. In the ladder type filter shown in FIG. 1, when n=4, that is, the ladder type filter was constructed using seven resonators similarly to the ladder type filter shown in FIG. 2. A plurality of these ladder-type filters were prepared, immersed in molten solder at a temperature of 260°C for 3 seconds, and then removed from the molten solder. After 10 minutes had passed, the voltage between the input terminal and the ground potential was measured. . Note that during the measurement, the input impedance was IMΩ/10 pF.
結果を、下記の第１表に示す、なお、比較のために、７
個の共振子の分極方向をアトランダムとした従来のラダ
ー型フィルタを複数個用意し、同様にして温度変化を与
えて入力端とアース電位との間の電圧を測定した。結果
を第１表に併せて示す、なお、第１表中の電圧の単位は
Ｖである。The results are shown in Table 1 below, and for comparison, 7
A plurality of conventional ladder-type filters were prepared in which the polarization directions of the resonators were random, and the voltage between the input terminal and the ground potential was measured by applying temperature changes in the same manner. The results are also shown in Table 1. The unit of voltage in Table 1 is V.
第 １ 表
第１表から明らかなように、共振子の分極方向をアトラ
ンダムとした従来品では焦電性に起因する高電圧が入力
端とアース電位との間にかなりの大きさで印加され、さ
らにその大きさが非常にばらついている。これに対して
、本実施例のラダー型フィルタでは「０」となることが
わかる。Table 1 As is clear from Table 1, in conventional products in which the polarization direction of the resonator is at random, a considerable amount of high voltage due to pyroelectricity is applied between the input terminal and the ground potential. , and their sizes vary widely. On the other hand, it can be seen that in the ladder type filter of this embodiment, the value is "0".
なお、本発明は、圧電セラミック板の両生面に電極を構
成した構造を有する共振子を用いたものに限らず、セラ
ミックス以外の他の圧電体からなる圧電板を用いたラダ
ー型フィルタにも適用することができる。Note that the present invention is not limited to those using a resonator having a structure in which electrodes are formed on the bidirectional surfaces of a piezoelectric ceramic plate, but can also be applied to a ladder type filter using a piezoelectric plate made of a piezoelectric material other than ceramics. can do.
また、分極方向は、本発明の条件を満たす限り、第１図
に矢印で示した方向と逆の場合であってもよい。Further, the polarization direction may be opposite to the direction indicated by the arrow in FIG. 1 as long as the conditions of the present invention are satisfied.
本発明によれば、直列腕の少なくとも一方の端部に配置
された直列共振子及び該直列共振子に接続された並列共
振子の圧電板の分極方向が、両共振子の接続点側から見
て同一方向とされているため、焦電効果により誘起され
た高電圧が該接続点側の入出力端側に印加されることを
確実に防止することができる。従って、はんだ付は等の
急激な温度変化がラダー型フィルタに与えられた場合で
あっても、接続される能動素子等の高電圧破壊を効果的
に防止することができる。According to the present invention, the polarization direction of the piezoelectric plates of the series resonator disposed at at least one end of the series arm and the parallel resonator connected to the series resonator is determined when viewed from the connection point side of both resonators. Since they are in the same direction, it is possible to reliably prevent high voltage induced by the pyroelectric effect from being applied to the input/output end side of the connection point. Therefore, even if the ladder type filter is subjected to a sudden temperature change such as during soldering, high voltage breakdown of connected active elements etc. can be effectively prevented.
また、直列腕に配置された複数個の直列共振子の圧電板
の分極方向を直列腕に沿って交互に逆極性とすれば、直
列共振子の焦電効果により誘起された高電圧の相乗的付
加を防止することができるため、接続される素子への高
電圧の印加をより一層効果的に防止することが可能とな
る。In addition, if the polarization direction of the piezoelectric plates of the plurality of series resonators arranged in the series arm is alternately reversed along the series arm, the synergistic effect of the high voltage induced by the pyroelectric effect of the series resonators Since the application of high voltage to the connected elements can be prevented even more effectively.
第１図は本発明の一実施例が適用されたラダー型フィル
タを示す回路図、第２図は従来のラダー型フィルタを説
明するための回路図、第３図は本発明が適用されるラダ
ー型フィルタの他の例を説明するための回路図である。
図におｔｌで、Ｘ ＋ ”” Ｘ−は直列共振子、Ｙｌ
〜Ｙ＋＋−＋ は並列共振子、Ｐ ＸＩ＋ Ｐ ＊！＋
’−”−’−’ ＋ Ｐ Ｘｌｌ＋Ｐ Ｆ＋＋ ・
−・−・・・−・、Ｐ□□、は分極方向を示す。
第３図Fig. 1 is a circuit diagram showing a ladder type filter to which an embodiment of the present invention is applied, Fig. 2 is a circuit diagram for explaining a conventional ladder type filter, and Fig. 3 is a circuit diagram showing a ladder type filter to which the present invention is applied. FIG. 3 is a circuit diagram for explaining another example of a type filter. In the figure, tl is X + "" X- is a series resonator, Yl
~Y++-+ is a parallel resonator, P XI+ P*! +
'-"-'-' + P Xll+P F++ ・
−・−・・・, P□□ indicate the polarization direction. Figure 3
Claims (2)
共振子で構成された並列腕とを有し、各共振子が圧電板
を用いて構成されているラダー型フィルタにおいて、 前記直列腕の少なくとも一方の端部に配置された直列共
振子及び該直列共振子に接続された並列共振子の圧電板
の分極方向が、前記直列腕の少なくとも一方端部に配置
された直列共振子と該直列共振子に接続された並列共振
子との接続点側からみて同一方向とされていることを特
徴とするラダー型フィルタ。(1) In a ladder type filter having a series arm composed of a plurality of series resonators and a parallel arm composed of parallel resonators, each resonator is composed of a piezoelectric plate, the above-mentioned A series resonator arranged at at least one end of the series arm, and a piezoelectric plate of a parallel resonator connected to the series resonator whose polarization direction is set at at least one end of the series arm. and a parallel resonator connected to the series resonator are oriented in the same direction when viewed from the connection point side.
方向が直列腕に沿って交互に逆方向とされていることを
特徴とする請求項１に記載のラダー型フィルタ。(2) The ladder type filter according to claim 1, wherein the polarization directions of the piezoelectric plates of the plurality of series resonators of the series arm are alternately opposite along the series arm.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2987190A JPH03234109A (en) | 1990-02-08 | 1990-02-08 | Ladder filter |
| US08/088,488 US5351021A (en) | 1990-02-08 | 1993-07-06 | Ladder-type piezoelectric filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2987190A JPH03234109A (en) | 1990-02-08 | 1990-02-08 | Ladder filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH03234109A true JPH03234109A (en) | 1991-10-18 |
Family
ID=12288038
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2987190A Pending JPH03234109A (en) | 1990-02-08 | 1990-02-08 | Ladder filter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH03234109A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009010932A (en) * | 2007-04-16 | 2009-01-15 | Avago Technologies General Ip (Singapore) Private Ltd | Bulk acoustic wave (baw) filter having reduced second harmonic generation and method of reducing second harmonic generation in baw filter |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02302114A (en) * | 1989-05-17 | 1990-12-14 | Matsushita Electric Ind Co Ltd | Filter |
-
1990
- 1990-02-08 JP JP2987190A patent/JPH03234109A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02302114A (en) * | 1989-05-17 | 1990-12-14 | Matsushita Electric Ind Co Ltd | Filter |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009010932A (en) * | 2007-04-16 | 2009-01-15 | Avago Technologies General Ip (Singapore) Private Ltd | Bulk acoustic wave (baw) filter having reduced second harmonic generation and method of reducing second harmonic generation in baw filter |
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