JPH02305015A - Surface acoustic wave multi-mode filter - Google Patents
Surface acoustic wave multi-mode filterInfo
- Publication number
- JPH02305015A JPH02305015A JP12562189A JP12562189A JPH02305015A JP H02305015 A JPH02305015 A JP H02305015A JP 12562189 A JP12562189 A JP 12562189A JP 12562189 A JP12562189 A JP 12562189A JP H02305015 A JPH02305015 A JP H02305015A
- Authority
- JP
- Japan
- Prior art keywords
- acoustic wave
- surface acoustic
- bus electrode
- width
- electrode
- 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
- 238000010897 surface acoustic wave method Methods 0.000 title claims abstract description 14
- 230000005540 biological transmission Effects 0.000 claims description 7
- 239000000758 substrate Substances 0.000 claims description 2
- 230000006866 deterioration Effects 0.000 abstract description 3
- 230000007423 decrease Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
Landscapes
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、交叉指状電極間の音響的結合を利用した弾性
表面波多重モードフィルタに関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a surface acoustic wave multimode filter that utilizes acoustic coupling between interdigital electrodes.
第２図に示すごとく、従来の弾性表面波多重モードフィ
ルタでは、多重モードフィルタの中心周波数が高くなる
程交叉指状電極２１の寸法が小形化し、これに伴ってバ
ス電極２２の幅ｇも小さくなり、バス電極２２のシート
抵抗が増大する。As shown in FIG. 2, in the conventional surface acoustic wave multimode filter, the higher the center frequency of the multimode filter, the smaller the dimensions of the interdigital electrode 21, and the smaller the width g of the bus electrode 22. Therefore, the sheet resistance of the bus electrode 22 increases.
上述した従来の弾性表面波多重モードフィルタは、中心
周波数か高くなるに従い、バス電極の幅ｇが小さくなり
、シート抵抗が増大し、帯域外減衰量が劣化するという
欠点がある。The above-described conventional surface acoustic wave multimode filter has the disadvantage that as the center frequency increases, the width g of the bus electrode decreases, the sheet resistance increases, and the out-of-band attenuation decreases.
本発明の弾性表面波多重モードフィルタは、圧電基板上
に配設した複数の交叉指状電極をもつ複数の共振子を弾
性表面波の伝搬方向と直角をなす向きに隣接させて配置
し、且つ隣接した前記共振子のバス電極を共通化した構
造を有する弾性表面波多重モードフィルタにおいて、伝
送特性の中心周波数をｆとして、前記共通化バス電極の
弾性表面波の伝搬方向に対する直角方向の幅ｇを、ｇ−
α−ｆ（α≧０．１ μｍ −ＭＥ−（Ｚ−’ ）なる
条件を満足するよう設定しである。The surface acoustic wave multi-mode filter of the present invention includes a plurality of resonators having a plurality of interdigitated electrodes arranged on a piezoelectric substrate and arranged adjacent to each other in a direction perpendicular to the propagation direction of the surface acoustic wave, and In a surface acoustic wave multimode filter having a structure in which the bus electrodes of the adjacent resonators are shared, the width g of the shared bus electrode in the direction perpendicular to the propagation direction of the surface acoustic wave, where f is the center frequency of the transmission characteristic. , g-
It is set to satisfy the condition α−f (α≧0.1 μm −ME−(Z−′)).
次に本発明について図面を参照して説明する。 Next, the present invention will be explained with reference to the drawings.
第１図は本発明の一実施例の電極パターンを示す上面図
である。参照番号１１は交叉指状電極を、１２はバス電
極をそれぞれ示し、バス電極１２の幅ｇは、条件ｇ＝ａ
・ｆ（ａ≧０．１ μｍ −ＭＨｚ−１，ｆ＝多重モー
ドフィルタの中心周波数（ＭＨｚ＞）を満足する値に設
定する。FIG. 1 is a top view showing an electrode pattern according to an embodiment of the present invention. Reference number 11 indicates an interdigital electrode, 12 indicates a bus electrode, and the width g of the bus electrode 12 is determined by the condition g=a.
- Set to a value that satisfies f (a≧0.1 μm −MHz−1, f=center frequency (MHz>) of the multimode filter.
第３図は、本実施例および従来の多重モードフィルタの
伝送特性を比較して示した特性図である。上記の条件を
満足させることにより、従来の多重モードフィルタの伝
送特性３１と比較して、本実施例の多重モードフィルタ
の伝送特性３２は帯域外減衰量に関して５ｄＢ程度向上
している。FIG. 3 is a characteristic diagram showing a comparison of the transmission characteristics of the present embodiment and the conventional multimode filter. By satisfying the above conditions, the transmission characteristic 32 of the multimode filter of this embodiment is improved by about 5 dB in terms of out-of-band attenuation compared to the transmission characteristic 31 of the conventional multimode filter.
この特性向上は、バス電極１２のシート抵抗を従来フィ
ルタよりも低減することによって得られたものである。This improvement in characteristics was achieved by reducing the sheet resistance of the bus electrode 12 compared to conventional filters.
以上説明したように本発明には、バス電極の幅ｇを条件
ｇ＝α−ｆ（α≧０．１７１ ｍ−Ｍ Ｈｚ−’ 。As explained above, in the present invention, the width g of the bus electrode is set under the condition g=α−f (α≧0.171 m−MHz−′).
ｆ＝多重モードフィルタの中心周波数ＭＨｚ＞で設定す
ることにより、高周波におけるバス電極部のシート抵抗
の増大に起因する帯域外減衰量の劣化を防ぐ効果がある
。By setting f=center frequency of the multimode filter MHz>, there is an effect of preventing deterioration of the out-of-band attenuation due to an increase in the sheet resistance of the bus electrode portion at high frequencies.
図面の簡単な説明
第１図は本発明の実施例のパターンを示す上面図、第２
図は、従来の弾性表面波多重モードフィルタのパターン
を示す上面図、第３図は本発明および従来の多重モード
フィルタの伝送特性を比較して示す特性図である。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top view showing a pattern of an embodiment of the present invention, and FIG.
The figure is a top view showing the pattern of a conventional surface acoustic wave multimode filter, and FIG. 3 is a characteristic diagram showing a comparison of the transmission characteristics of the present invention and the conventional multimode filter.
１１．２１・・・交叉指状電極、１２．２２・・・バス
電極、３１．３２・・・伝送特性。11.21... Cross-finger electrode, 12.22... Bus electrode, 31.32... Transmission characteristics.
Claims (1)
共振子を弾性表面波の伝搬方向と直角をなす向きに隣接
させて配置し、且つ隣接した前記共振子のバス電極を共
通化した構造を有する弾性表面波多重モードフィルタに
おいて、伝送特性の中心周波数をｆとして、前記共通化
バス電極の弾性表面波の伝搬方向に対する直角方向の幅
ｇを、ｇ＝α・ｆ（α≧０．１μｍ・ＭＨ＿ｚ＾−＾１
）なる条件を満足するよう設定してあることを特徴とす
る弾性表面波多重モードフィルタ。A plurality of resonators having a plurality of interdigitated electrodes arranged on a piezoelectric substrate are arranged adjacently in a direction perpendicular to the propagation direction of a surface acoustic wave, and the bus electrodes of the adjacent resonators are shared. In the surface acoustic wave multimode filter having a structure, where f is the center frequency of the transmission characteristic, the width g of the common bus electrode in the direction perpendicular to the propagation direction of the surface acoustic wave is g=α・f (α≧0 .1μm・MH_＾＾-＾1
) A surface acoustic wave multimode filter characterized by being set to satisfy the following conditions.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12562189A JPH02305015A (en) | 1989-05-18 | 1989-05-18 | Surface acoustic wave multi-mode filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12562189A JPH02305015A (en) | 1989-05-18 | 1989-05-18 | Surface acoustic wave multi-mode filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02305015A true JPH02305015A (en) | 1990-12-18 |
Family
ID=14914602
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12562189A Pending JPH02305015A (en) | 1989-05-18 | 1989-05-18 | Surface acoustic wave multi-mode filter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02305015A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5864262A (en) * | 1995-07-25 | 1999-01-26 | Murata Manufacturing Co. Ltd. | Surface acoustic wave device having one-port and double mode SAW resonators |
-
1989
- 1989-05-18 JP JP12562189A patent/JPH02305015A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5864262A (en) * | 1995-07-25 | 1999-01-26 | Murata Manufacturing Co. Ltd. | Surface acoustic wave device having one-port and double mode SAW resonators |
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