JPH06244676A - Multi-stage connecting saw filter - Google Patents
Multi-stage connecting saw filterInfo
- Publication number
- JPH06244676A JPH06244676A JP5507593A JP5507593A JPH06244676A JP H06244676 A JPH06244676 A JP H06244676A JP 5507593 A JP5507593 A JP 5507593A JP 5507593 A JP5507593 A JP 5507593A JP H06244676 A JPH06244676 A JP H06244676A
- Authority
- JP
- Japan
- Prior art keywords
- surface acoustic
- acoustic wave
- wave filter
- electrode
- filter element
- 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
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は圧電基板上を伝播する弾
性表面波を応用した弾性表面波フィルタに関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave filter to which surface acoustic waves propagating on a piezoelectric substrate are applied.
【0002】[0002]
【従来の技術】従来技術を図2,図3とともに説明す
る。図2は、従来の横モード結合の多段接続弾性表面波
フィルタの平面図である。圧電基板1は薄板状のLiN
bO3からなり、矩形形状に加工されている。この圧電
基板1の表面には、交差指電極41a,42a並びに反
射器電極41b,41c,42b,42cが形成されて
おり、弾性表面波共振器を2つ並列に設けてなる2対の
共振器型弾性表面波フィルタ素子41,42を構成して
いる。上記交差指電極41a,42aは連結電極43で
電気的に接続されており、全体として多段接続共振子型
弾性表面波フィルタが構成されている。2つの弾性表面
波フィルタ41,42間には電磁シールド電極51,5
2が前記連結電極43の近傍まで形成されており、両フ
ィルタ間を直接伝播する電磁波(一般に直達波と称され
る)あるいはバルク波等の他の弾性波の影響を互いに防
ぐ目的で設けられている。2. Description of the Related Art A conventional technique will be described with reference to FIGS. FIG. 2 is a plan view of a conventional transverse mode coupled multi-stage connection surface acoustic wave filter. The piezoelectric substrate 1 is a thin plate of LiN
It is made of bO 3 and is processed into a rectangular shape. Interdigitated electrodes 41a, 42a and reflector electrodes 41b, 41c, 42b, 42c are formed on the surface of the piezoelectric substrate 1, and two pairs of resonators are provided in which two surface acoustic wave resonators are provided in parallel. The surface acoustic wave filter elements 41 and 42 are configured. The interdigital electrodes 41a and 42a are electrically connected by a connecting electrode 43, and a multistage resonator type surface acoustic wave filter is configured as a whole. Electromagnetic shield electrodes 51, 5 are provided between the two surface acoustic wave filters 41, 42.
2 is formed up to the vicinity of the connecting electrode 43, and is provided for the purpose of mutually preventing the influence of electromagnetic waves (generally called direct waves) directly propagating between both filters or other elastic waves such as bulk waves. There is.
【0003】図3は従来の縦モード結合の多段接続弾性
表面波フィルタの平面図である。圧電基板1は薄板状の
LiNbO3からなり、矩形形状に加工されている。こ
の圧電基板1の表面には、交差指電極61a,61bが
直列に配置されており、これら交差指電極の両側に反射
器電極61c,61dが形成されており、縦モード結合
の弾性表面波フィルタ素子61が構成され、これと平行
に、交差指電極62a,62bが直列に配置され、これ
ら交差指電極の両側に反射器電極62c,62dが形成
された縦モード結合の弾性表面波フィルタ素子61が構
成され、これら2つの弾性表面波フィルタ素子は連結電
極63で電気的に接続されている。また、上記従来例と
同じく2つの弾性表面波フィルタ41,42間には電磁
シールド電極51,52が前記連結電極43の近傍まで
形成されており、全体として多段接続共振子型弾性表面
波フィルタが構成されている。FIG. 3 is a plan view of a conventional multi-stage surface acoustic wave filter of longitudinal mode coupling. The piezoelectric substrate 1 is made of thin plate LiNbO 3 and is processed into a rectangular shape. Interdigitated electrodes 61a and 61b are arranged in series on the surface of the piezoelectric substrate 1, and reflector electrodes 61c and 61d are formed on both sides of these interdigitated electrodes, which are surface acoustic wave filters of longitudinal mode coupling. The element 61 is configured, and the interdigital electrodes 62a and 62b are arranged in parallel with the element 61, and the reflector electrodes 62c and 62d are formed on both sides of the interdigital electrodes, respectively, and the longitudinal mode coupling surface acoustic wave filter element 61 is formed. And the two surface acoustic wave filter elements are electrically connected by the connecting electrode 63. Further, electromagnetic shield electrodes 51, 52 are formed between the two surface acoustic wave filters 41, 42 up to the vicinity of the connecting electrode 43 as in the conventional example, and the multi-stage connection resonator type surface acoustic wave filter is formed as a whole. It is configured.
【0004】なお、図示していないがこれら弾性表面波
フィルタはセラミック等のパッケージに収納され、最後
に金属性のフタとパッケージの金属層とがシーム溶接等
で気密封止される。Although not shown, these surface acoustic wave filters are housed in a package made of ceramic or the like, and finally the metallic lid and the metal layer of the package are hermetically sealed by seam welding or the like.
【0005】[0005]
【発明が解決しようとする課題】横モード結合弾性表面
波フィルタの周波数通過帯域特性は、図5に示すように
一般的に通過帯域幅を広くとりにくく、帯域幅を広げよ
うとすると通過帯域特性がAで示すように双峰特性とな
り、群遅延特性を悪化させていた。また、縦モード結合
のそれは、図6に示すように一般的に横モード結合のそ
れに比べて単峰特性で、通過帯域幅を広くとることがで
きるが、通過帯域外においては、サイドロープの影響に
よると考えられるスプリアスが数多く発生し、減衰特性
を悪化させていた。The frequency pass band characteristic of the transverse mode coupled surface acoustic wave filter is generally difficult to obtain a wide pass band width as shown in FIG. Shows a bimodal characteristic as shown by A, and deteriorates the group delay characteristic. Further, as shown in FIG. 6, the longitudinal mode coupling generally has a single-peak characteristic as compared with that of the transverse mode coupling and can have a wide pass band width. However, outside the pass band, the influence of the side ropes is large. A lot of spurious that is thought to be caused was generated and deteriorated the damping characteristic.
【0006】本発明は上記問題点を解決するためになさ
れたもので、多段接続型の弾性表面波フィルタにおい
て、周波数通過帯域特性並びに群遅延特性が良好で、実
用的な減衰特性を得ることができる弾性表面波フィルタ
を得ることを目的とする。The present invention has been made to solve the above problems, and in a multi-stage connection type surface acoustic wave filter, the frequency pass band characteristic and the group delay characteristic are excellent, and a practical attenuation characteristic can be obtained. The purpose is to obtain a surface acoustic wave filter that can be used.
【0007】[0007]
【課題を解決するための手段】上記問題点を解決するた
めに、本発明による多段接続型弾性表面波フィルタは、
圧電基板の表面に、弾性表面波を励起する交差指電極を
少なくとも2つ直列に配置し、これら交差指電極の両側
に励起された弾性表面波を反射する反射器電極を有した
弾性表面波フィルタ素子を設けるとともに、弾性表面波
を励起する交差指電極とこの交差指電極の両側に励起さ
れた弾性表面波を反射する反射器を有する弾性表面波共
振器を2つ並列に配置した弾性表面波フィルタ素子を少
なくとも2つ並列に配置し、各弾性表面波フィルタ素子
の交差指電極を電気的に接続したことを特徴とする。な
お、各弾性表面波フィルタ素子の接続に伴いインピーダ
ンス等の整合が必要な場合、両フィルタ素子の交差指電
極をつなぐ連結電極にコイル、コンデンサ等からなるイ
ンピーダンス整合回路を設けるとよい。In order to solve the above-mentioned problems, a multi-stage connection type surface acoustic wave filter according to the present invention comprises:
A surface acoustic wave filter having at least two interdigital electrodes for exciting surface acoustic waves arranged in series on the surface of a piezoelectric substrate, and having reflector electrodes for reflecting the surface acoustic waves excited on both sides of these interdigital electrodes. A surface acoustic wave in which two elements are provided and two surface acoustic wave resonators having a crossing finger electrode for exciting the surface acoustic wave and reflectors for reflecting the surface acoustic wave excited on both sides of the crossing finger electrode are arranged in parallel. At least two filter elements are arranged in parallel, and the interdigital electrodes of the surface acoustic wave filter elements are electrically connected. When matching of impedance and the like is required due to the connection of the surface acoustic wave filter elements, it is preferable to provide an impedance matching circuit including a coil and a capacitor on the connecting electrode that connects the cross finger electrodes of both filter elements.
【0008】[0008]
【作用】圧電基板の表面に、少なくとも横モード結合の
弾性表面波フィルタ素子と縦モード結合の弾性表面波フ
ィルタ素子を形成しているので、横モード結合の良好な
減衰特性が縦モード結合の通過帯域外に発生するスプリ
アスと抑制し、また縦モード結合の単峰特性である通過
帯域特性が横モード結合の双峰特性の発生を減じるため
両者の短所を補完し合う。図4は本発明実施品の周波数
通過帯域特性を示すグラフであるが、図5に示す横モー
ド結合の弾性表面波フィルタの周波数通過帯域特性(図
4に示すグラフと同じ中心周波数)と、図6に示す縦モ
ード結合の弾性表面波フィルタの周波数帯域特性(図4
に示すグラフと同じ中心周波数)の短所を相互に補完し
あっていることが分かる。Since at least the transverse mode coupled surface acoustic wave filter element and the longitudinal mode coupled surface acoustic wave filter element are formed on the surface of the piezoelectric substrate, excellent transverse mode coupling attenuation characteristics can be obtained by passing through the longitudinal mode coupling. It suppresses spurious that occurs outside the band, and the pass-band characteristic, which is the unimodal characteristic of the longitudinal mode coupling, reduces the occurrence of the bimodal characteristic of the transverse mode coupling, which complements the disadvantages of both. FIG. 4 is a graph showing the frequency pass band characteristic of the product of the present invention. FIG. 4 is a graph showing the frequency pass band characteristic of the surface acoustic wave filter of the transverse mode coupling shown in FIG. 5 (the same center frequency as the graph shown in FIG. 4). Frequency band characteristics of the longitudinal mode coupled surface acoustic wave filter shown in FIG.
It can be seen that the disadvantages of the same center frequency as in the graph shown in (4) complement each other.
【0009】[0009]
【実施例】本発明による実施例を図面とともに説明す
る。図1は本発明による弾性表面波フィルタの平面図で
ある。圧電基板1は薄板状のLiNbO3からなり、矩
形形状に加工されている。この圧電基板1の表面には、
弾性表面波共振器を2つ並列に設けてなる横モード結合
の弾性表面波フィルタ素子21が形成されており、この
弾性表面波フィルタ素子21は、交差指電極21a並び
にこの交差指電極から励起される弾性表面波伝播方向の
両側に反射器電極21b,21cを有している。また、
この弾性表面波フィルタ素子21に並列して縦モード結
合の弾性表面波フィルタ素子22が形成されており、こ
の弾性表面波フィルタ素子22は、交差指電極22a,
22bを直列に配置し、これら交差指電極の弾性表面波
の伝播方向両側に反射器電極22c,22dを有してい
る。交差指電極21aの他端と交差指電極22aの一端
は連結電極23で電気的に接続されており、また、入出
力電極24と交差指電極21aの一端、入出力電極26
と交差指電極22bはそれぞれ電気的に接続され、電極
が外部に導出されている。さらに弾性表面波フィルタ素
子間には電磁シールド電極31,32が形成されてお
り、それぞれ弾性表面波フィルタ素子21の反射器電極
21b端部から前記連結電極近傍までと、反射器電極2
2c端部から同じく連結電極近傍まで延びている。これ
ら両弾性表面波フィルタ素子で全体として多段接続型弾
性表面波フィルタ2を構成している。これら両弾性表面
波フィルタ素子の中心周波数は同じ周波数になるように
設計すればよいが、要求される通過帯域の周波数特性の
仕様に応じて周波数をずらす必要のある場合がある。な
お、図示していないが、アルミナ等のセラミックからな
り、外部への引出電極を有するパッケージに弾性表面波
フィルタ2を収納し、必要な電気的接続を行った後、金
属性のフタを前記パッケージの金属枠にシーム溶接等に
より接合し、気密封止される。Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a surface acoustic wave filter according to the present invention. The piezoelectric substrate 1 is made of thin plate LiNbO 3 and is processed into a rectangular shape. On the surface of this piezoelectric substrate 1,
A transverse mode coupled surface acoustic wave filter element 21 having two surface acoustic wave resonators provided in parallel is formed. The surface acoustic wave filter element 21 is excited by the interdigital electrode 21a and the interdigital electrode. Reflector electrodes 21b and 21c are provided on both sides in the surface acoustic wave propagation direction. Also,
A longitudinal mode coupled surface acoustic wave filter element 22 is formed in parallel with the surface acoustic wave filter element 21, and the surface acoustic wave filter element 22 includes the interdigital electrode 22a,
22b are arranged in series, and reflector electrodes 22c and 22d are provided on both sides of these interdigital electrodes in the surface acoustic wave propagation direction. The other end of the crossing finger electrode 21a and one end of the crossing finger electrode 22a are electrically connected to each other by a connecting electrode 23, and the input / output electrode 24 and one end of the crossing finger electrode 21a and the input / output electrode 26 are connected.
And the cross finger electrode 22b are electrically connected to each other, and the electrodes are led to the outside. Further, electromagnetic shield electrodes 31 and 32 are formed between the surface acoustic wave filter elements, and respectively from the end of the reflector electrode 21b of the surface acoustic wave filter element 21 to the vicinity of the connecting electrode and the reflector electrode 2.
Similarly, it extends from the end 2c to the vicinity of the connecting electrode. These two surface acoustic wave filter elements constitute a multi-stage connection type surface acoustic wave filter 2 as a whole. The center frequencies of these surface acoustic wave filter elements may be designed to be the same frequency, but it may be necessary to shift the frequencies in accordance with the specifications of the required frequency characteristics of the pass band. Although not shown, the surface acoustic wave filter 2 is housed in a package made of ceramics such as alumina and having an extraction electrode to the outside, and after a necessary electrical connection is made, the metallic lid is attached to the package. The metal frame is joined to the metal frame by seam welding or the like and hermetically sealed.
【0010】なお、各弾性表面波フィルタ素子の接続に
伴いインピーダンス等の整合が必要な場合、例えば図1
に示すように両フィルタ素子の交差指電極をつなぐ連結
電極から延出された中央部引出電極33にコイル、コン
デンサ等からなるインピーダンス整合回路を設けるとよ
い。また、上記実施例では、縦モード結合型と横モード
結合型の両弾性表面波フィルタ素子それぞれ1つの組み
合わせを示したが、これに限らず、要求される電気的特
性等の仕様によって一方を2つ、他方を1つの組み合わ
せ、あるいはそれ以上の組み合わせを行ってもよい。When matching of impedances and the like is required in connection with each surface acoustic wave filter element, for example, as shown in FIG.
As shown in, it is preferable to provide an impedance matching circuit including a coil, a capacitor and the like on the central extraction electrode 33 extending from the connecting electrode that connects the interdigital electrodes of both filter elements. Further, in the above-mentioned embodiment, one combination of both the longitudinal mode coupling type and the transverse mode coupling type surface acoustic wave filter element is shown, but the present invention is not limited to this, and one of the two may be selected depending on the specifications such as required electrical characteristics. One and the other may be combined in one or more combinations.
【0011】[0011]
【発明の効果】圧電基板の表面に、少なくとも横モード
結合の弾性表面波フィルタ素子と縦モード結合の弾性表
面波フィルタ素子を形成しているので、横モード結合の
良好な減衰特性が縦モード結合の通過帯域外に発生する
スプリアスと抑制し、また縦モード結合の単峰特性であ
る通過帯域特性が横モード結合の双峰特性の発生を減じ
るため両者の短所を補完し、また、同一モードで多段接
続した場合に生じ易い段間での結合によるスプリアスが
発生しにくく、全体として周波数通過帯域特性、群遅延
特性あるいは減衰特性等がバランスよく調整された良好
な電気的特性の多段接続型弾性表面波フィルタを得るこ
とができる。Since at least the surface acoustic wave filter element of the transverse mode coupling and the surface acoustic wave filter element of the longitudinal mode coupling are formed on the surface of the piezoelectric substrate, the excellent attenuation characteristic of the transverse mode coupling has the longitudinal mode coupling. Suppresses spurious waves that occur outside the passband of L, and the passband characteristic, which is the unimodal characteristic of the longitudinal mode coupling, reduces the occurrence of the bimodal characteristic of the transverse mode coupling. Multi-stage elastic surface with good electrical characteristics, in which spurious due to coupling between stages, which is likely to occur when connecting in multiple stages, is hard to occur, and overall good balance of frequency pass band characteristics, group delay characteristics, attenuation characteristics, etc. A wave filter can be obtained.
【図1】実施例を示す平面図。FIG. 1 is a plan view showing an embodiment.
【図2】従来例を示す平面図。FIG. 2 is a plan view showing a conventional example.
【図3】従来例を示す平面図。FIG. 3 is a plan view showing a conventional example.
【図4】本発明品による周波数通過帯域特性を示すグラ
フ。FIG. 4 is a graph showing frequency pass band characteristics according to the present invention.
【図5】図2に示す従来品による周波数通過帯域特性を
示すグラフ。5 is a graph showing frequency pass band characteristics of the conventional product shown in FIG.
【図6】図3に示す従来品による周波数通過帯域特性を
示すグラフ。6 is a graph showing frequency pass band characteristics of the conventional product shown in FIG.
1 圧電基板 21,41,42 横モード結合弾性表面波フィルタ素
子 22,61,62 縦モード結合弾性表面波フィルタ素
子 21a,22a,22b,41a,42a,61a,6
1b,62a,62b交差指電極 21b,21c,22c,22d,41b,41c,4
2b,42c,61c,61d,62c,62d 反射
器電極 31,32,51,52,71,72,73,74 電
磁シールド電極1 Piezoelectric Substrate 21, 41, 42 Transverse Mode Coupling Surface Acoustic Wave Filter Element 22, 61, 62 Longitudinal Mode Coupling Surface Acoustic Wave Filter Element 21a, 22a, 22b, 41a, 42a, 61a, 6
1b, 62a, 62b Interdigital finger electrodes 21b, 21c, 22c, 22d, 41b, 41c, 4
2b, 42c, 61c, 61d, 62c, 62d Reflector electrode 31, 32, 51, 52, 71, 72, 73, 74 Electromagnetic shield electrode
Claims (1)
る交差指電極を少なくとも2つ直列に配置し、これら交
差指電極の両側に励起された弾性表面波を反射する反射
器電極を有した縦モード結合型弾性表面波フィルタ素子
を設けるとともに、弾性表面波を励起する交差指電極と
この交差指電極の両側に励起された弾性表面波を反射す
る反射器を有する弾性表面波共振器を2つ並列に配置し
た横モード結合型弾性表面波フィルタ素子を少なくとも
2つ選択的に並列配置し、各弾性表面波フィルタ素子の
交差指電極を電気的に接続したことを特徴とする多段接
続型弾性表面波フィルタ。1. A piezoelectric substrate is provided with at least two interdigital electrodes for exciting surface acoustic waves arranged in series on a surface of a piezoelectric substrate, and reflector electrodes for reflecting the excited surface acoustic waves are provided on both sides of these interdigital electrodes. In addition to providing the longitudinal mode coupling type surface acoustic wave filter element described above, a surface acoustic wave resonator having an interdigital electrode for exciting the surface acoustic wave and a reflector for reflecting the surface acoustic wave excited on both sides of the interdigital electrode is provided. At least two transverse mode coupling type surface acoustic wave filter elements arranged in parallel are selectively arranged in parallel, and the cross finger electrodes of each surface acoustic wave filter element are electrically connected. Surface acoustic wave filter.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP5507593A JPH06244676A (en) | 1993-02-19 | 1993-02-19 | Multi-stage connecting saw filter |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP5507593A JPH06244676A (en) | 1993-02-19 | 1993-02-19 | Multi-stage connecting saw filter |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH06244676A true JPH06244676A (en) | 1994-09-02 |
Family
ID=12988586
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP5507593A Pending JPH06244676A (en) | 1993-02-19 | 1993-02-19 | Multi-stage connecting saw filter |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH06244676A (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1996032777A1 (en) * | 1995-04-11 | 1996-10-17 | Japan Energy Corporation | Surface acoustic wave device |
EP0760556A1 (en) * | 1995-08-28 | 1997-03-05 | Motorola, Inc. | Acoustic wave filter with filter-shaping element and method |
US5699028A (en) * | 1994-05-11 | 1997-12-16 | Murata Manufacturing Co., Ltd. | Surface acoustic-wave resonator filter having shifted resonant frequencies |
WO2018016467A1 (en) * | 2016-07-18 | 2018-01-25 | Skyworks Filter Solutions Japan Co., Ltd. | Saw-based electronic elements and filter devices |
-
1993
- 1993-02-19 JP JP5507593A patent/JPH06244676A/en active Pending
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5699028A (en) * | 1994-05-11 | 1997-12-16 | Murata Manufacturing Co., Ltd. | Surface acoustic-wave resonator filter having shifted resonant frequencies |
WO1996032777A1 (en) * | 1995-04-11 | 1996-10-17 | Japan Energy Corporation | Surface acoustic wave device |
US5850167A (en) * | 1995-04-11 | 1998-12-15 | Kinseki, Limited | Surface acoustic wave device |
EP0760556A1 (en) * | 1995-08-28 | 1997-03-05 | Motorola, Inc. | Acoustic wave filter with filter-shaping element and method |
WO2018016467A1 (en) * | 2016-07-18 | 2018-01-25 | Skyworks Filter Solutions Japan Co., Ltd. | Saw-based electronic elements and filter devices |
US10778183B2 (en) | 2016-07-18 | 2020-09-15 | Skyworks Filter Solutions Japan Co., Ltd. | Saw-based electronic elements and filter devices |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US5999069A (en) | Surface acoustic wave ladder filter having a parallel resonator with a larger electrostatic capacitance | |
US9847770B2 (en) | Elastic wave resonator, elastic wave filter apparatus, and duplexer | |
US6127769A (en) | Surface acoustic wave device | |
JPH01260911A (en) | Composite filter for surface acoustic wave resonator | |
US5864262A (en) | Surface acoustic wave device having one-port and double mode SAW resonators | |
JPH08265087A (en) | Surface acoustic wave filter | |
JPH06260876A (en) | Surface acoustic wave filter | |
US7843285B2 (en) | Piezoelectric thin-film filter | |
US20010013817A1 (en) | Surface acoustic wave filter | |
JP2002314366A (en) | Surface acoustic wave filter, surface acoustic wave device and communication equipment | |
JP3385169B2 (en) | Surface acoustic wave multimode filter | |
US6297713B1 (en) | Surface acoustic wave device with split electrodes and outermost electrodes of a different width than the split electrodes | |
EP0637873A2 (en) | SAW filter | |
JP7386741B2 (en) | Filters, duplexers and communication equipment | |
JP3377902B2 (en) | Surface acoustic wave filter | |
US20090201105A1 (en) | Acoustic wave device | |
JPH06244676A (en) | Multi-stage connecting saw filter | |
JP3253568B2 (en) | Multi-stage surface acoustic wave filter | |
JP3915322B2 (en) | Surface acoustic wave filter | |
US6049260A (en) | Surface acoustic wave filter having parameters optimized to suppress spurious signals | |
JPH06177703A (en) | Longitudinal triplex mode saw filter | |
JP2001230657A (en) | Surface acoustic wave filter | |
JPH10261935A (en) | Surface acoustic wave element | |
JPH07154199A (en) | Resonator type surface acoustic wave filter | |
JPH04373304A (en) | Surface acoustic wave filter |