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EP0520002A1 - Convertisseur d'ondes de surface, particulierement du type a doigts doubles, avec suppression des reflexions des doigts de convertisseur terminaux - Google Patents

Convertisseur d'ondes de surface, particulierement du type a doigts doubles, avec suppression des reflexions des doigts de convertisseur terminaux

Info

Publication number
EP0520002A1
EP0520002A1 EP91906400A EP91906400A EP0520002A1 EP 0520002 A1 EP0520002 A1 EP 0520002A1 EP 91906400 A EP91906400 A EP 91906400A EP 91906400 A EP91906400 A EP 91906400A EP 0520002 A1 EP0520002 A1 EP 0520002A1
Authority
EP
European Patent Office
Prior art keywords
transducer
finger
fingers
last
terminal
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.)
Ceased
Application number
EP91906400A
Other languages
German (de)
English (en)
Inventor
Oswald Dr. Männer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Siemens Corp
Original Assignee
Siemens AG
Siemens Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Siemens AG, Siemens Corp filed Critical Siemens AG
Publication of EP0520002A1 publication Critical patent/EP0520002A1/fr
Ceased legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02818—Means for compensation or elimination of undesirable effects
    • H03H9/02842—Means for compensation or elimination of undesirable effects of reflections

Definitions

  • the present invention relates to surface wave transducers with the features of the preamble of patent claim 1.
  • the center distances of successive transducer fingers is a quarter (or a sixth) of the acoustic wavelength of the surface wave to which the respective one is concerned Transducer is tuned, namely the wavelength of the acoustic wave in the substrate material of the transducer.
  • the center distances of adjacent groups of two (or three) equally polarized neighboring fingers, ie the center distances of the alternating split fingers, is again equal to half the wavelength as in the simple converter.
  • Another type of converter with suppression of internal reflections of the ultrasonic waves is the lambda third-finger arrangement.
  • the reflections of fingers of an interdigital transducer are those described in DE-B-28 39 851. Weighted fingers of the region of the transducer end are directed obliquely to the main axis of the wave propagation with substantial portions of the length of these fingers, so that these fingers with these inclined portions of their finger lengths reflect ultrasound waves impinging on them obliquely, ie do not reflect back into themselves.
  • a still further method is (Trans. IECE Jap. Vol 64-C (1981) pp. 437-438) to shorten a few terminal fingers in relation to the mutual spacing of the opposing busbars and to eliminate the "missing" finger length replacing one floating finger each, however floating potentials are problematic in many applications.
  • the object of the present invention is to provide measures with which such reflection effects occurring at the ends of a transducer are suppressed, and without other known operational disadvantages occurring.
  • the present invention is based on the knowledge that - based on the usual scheme of the width and positions of the transducer fingers in the interior of the transducer corresponding to the given design specification - by changing the finger width and finger position of the last transducer finger at the relevant end of the transducer, preferably the last two to four fingers, a satisfactory reflection suppression of reflections from terminal transducer fingers can be achieved.
  • This measure is primarily provided at the opposite ends of two such transducers of a filter.
  • "incorrect positioning" and / or "incorrect dimensioning of the finger width" of the last finger / the last fingers eliminates reflections which nevertheless occur at the converter end despite the low-reflection finger arrangement of the transducer fingers.
  • the invention is even more applicable to transducers with (in contrast to split fingers) single fingers.
  • the measure according to the invention avoids the known phase front distortions which occur, for example, in an embodiment with fingers that are gradually shortened.
  • This version with gradually shortened fingers or the other known measures for suppressing the reflections of terminal fingers already mentioned above can, on the other hand, be carried out at the opposite end, ie at the end of a transducer facing the sump, without any noteworthy interference with the desired transmission. quality of the filter.
  • the in a converter with the structure specified for the present application e.g. Split finger structure and reflections that occur are calculated according to methods of the prior art (IEEE Ultrason. Symp. Proc. (1985) pp. 78-81) for interdigital transducers with predefined different finger positions and finger widths of terminal transducer fingers (for a given frequency range). This is done using the iterative least squares method. The iteration is terminated as soon as a geometry of four positions or finger width deviations has been achieved which results in satisfactorily low reflections (at the terminal transducer fingers). It is then the dimensions to be used for the individual case for the finger widths and for the incorrect positioning of the selected terminal transducer fingers, i.e. this results in the optimized deviations of dimensions and positions of the terminal transducer fingers compared to the transducer fingers of the diagram of the middle-sized transducer fingers.
  • the relevant terminal transducer fingers are connected to one and the same busbar, which is in particular grounded. Wave phase fronts are not disturbed by the measure according to the invention, there are no floating potentials and such converters or filters designed according to the invention can be produced using the conventional technological measures of lithography.
  • the deviations for the finger widths are between up to almost double and approximately one fifth to one tenth of the finger widths of the transducer fingers of the scheme, the lithography for high frequencies determining the limit for the smallest width of a transducer finger.
  • the changes in the spaces between the fingers are roughly the same variation. rich. Numerical examples can make the orders of magnitude clearer.
  • Terminal fingers designed according to the invention have the following dimensions:
  • the fingers and spacing for the fingers of the transducer scheme are as follows:
  • Figure 1 shows a surface acoustic wave filter with two transducers
  • FIG. 2 shows a first embodiment of a converter
  • FIG. 3 shows an embodiment containing the invention and combining a known measure.
  • FIG. 1 shows schematically a surface acoustic wave filter 1 with a plate-shaped substrate 2 and with it on the surface of the substrate located interdigital transducers 3 and 4 are shown.
  • the double arrow 5 indicates the axis of the main direction of propagation of the acoustic waves, which is generated by one of the two transducers as a transmitting transducer and received by the other transducer as a receiving transducer.
  • FIG. 2 shows one of the converters of the filter of FIG. 1, for example the converter 4.
  • the transducer fingers F which are electrically connected to one or the other busbar can be seen.
  • F Q is the transducer finger corresponding to the predefined scheme of the transducer.
  • these transducer fingers F Q are regularly positioned with respect to one another and have the same finger width. They fill the middle part of converter 4 and, in the exemplary embodiment in FIG. 2, are arranged and distributed relative to one another in accordance with a lambda third converter.
  • these fingers F Q can also be arranged at such differing distances and can be designed in accordance with changing finger widths, namely as is well known to a person skilled in the art for a dispersive transducer.
  • a converter of this embodiment is also part of the invention.
  • the transducer 4 of FIG. 2 has positional transducer fingers F 1 , F 2 and F 2, positioned according to the invention and measured with respect to the finger width. It can be clearly seen from FIG. 2 that both the finger widths and the distances between the fingers and the finger F to the neighboring finger F-. are obviously differently dimensioned, specifically different from one another and different from the positions and finger widths of the fingers F .... This is the characteristic of the invention.
  • the two fingers F, and F 2 which are narrower than a finger F .., are also at a comparatively very small distance from one another. In contrast, the distance between the fingers F 1 and 2 is larger, but nevertheless smaller than the distance between fingers F 0 the finger F ,.
  • the finger F is wider than a finger F Q.
  • the distance between the finger F and the adjacent finger F Q that is to say the first finger F 0 corresponding to the diagram of the transducer, is again smaller than the usual finger distance between adjacent fingers F 1.
  • the other end of the transducer 4 has the corresponding fingers F, ', F' 1 and, which are dimensioned and positioned according to the invention
  • the fingers F,, F 2 and F_ are preferably connected to one and the same busbar 11, that is to say they are at the same potential, which is in particular the ground potential.
  • FIG. 3 shows one which also corresponds to the invention
  • the transducer has fingers F, which are arranged and selected in accordance with a split finger transducer.
  • the fingers F., F. 2 and F. are again the final transducer fingers, which are positioned according to the invention and are dimensioned with regard to their finger width.
  • the iteration method described above has resulted in a very narrow finger F ..,, also a very narrow finger F ..., and a wider finger F, 2 , but the latter finger is nevertheless narrower than a finger F Q.
  • the finger F n different distances of the finger F,, F 2 z ** Pi and the finger 13 adjacent finger F Q can be recognized.
  • the end 31 of the transducer 3 opposite this configuration according to the invention is designed with gradually shortened fingers instead of according to the invention according to the known prior art specified above. If the transducers of FIGS. 2 and 3, as they are oriented in their figures, are in the filter 1 of FIG. 1, the end of the transducer 3 stands with its fingers F 1, F 2, and F., and the end of the transducer 4 with his fingers F,, F and F, opposite each other. The otherwise on terminal fingers of the inter Reflections occurring with digital transducers do not occur here according to the invention, or they are strongly suppressed. Because of the fingers F ,, F 2 , F .. and F,,, P-

Landscapes

  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)

Abstract

Convertisseur d'ondes de surface avec des positions et des largeurs des doigts terminaux F1, F2 et F3 modifiées par rapport à celles des autres doigts de convertisseur, cet agencement étant destiné à supprimer les réflexions qui autrement se produiraient au niveau de ces doigts terminaux.
EP91906400A 1990-03-30 1991-03-28 Convertisseur d'ondes de surface, particulierement du type a doigts doubles, avec suppression des reflexions des doigts de convertisseur terminaux Ceased EP0520002A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4010310A DE4010310A1 (de) 1990-03-30 1990-03-30 Oberflaechenwellenwandler, insbesondere in splitfinger-ausfuehrung, mit unterdrueckung von reflexionen endstaendiger wandlerfinger
DE4010310 1990-03-30

Publications (1)

Publication Number Publication Date
EP0520002A1 true EP0520002A1 (fr) 1992-12-30

Family

ID=6403442

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91906400A Ceased EP0520002A1 (fr) 1990-03-30 1991-03-28 Convertisseur d'ondes de surface, particulierement du type a doigts doubles, avec suppression des reflexions des doigts de convertisseur terminaux

Country Status (5)

Country Link
US (1) US5304965A (fr)
EP (1) EP0520002A1 (fr)
JP (1) JPH05505081A (fr)
DE (1) DE4010310A1 (fr)
WO (1) WO1991015897A1 (fr)

Families Citing this family (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0685597A (ja) * 1992-09-02 1994-03-25 Mitsubishi Electric Corp 弾性表面波装置
JP3237387B2 (ja) * 1994-04-12 2001-12-10 株式会社村田製作所 弾性表面波共振子フィルタ
GB2289180B (en) * 1994-04-25 1998-08-12 Advanced Saw Prod Sa Saw filter
DE69636897T2 (de) * 1995-05-29 2007-10-25 Sanyo Electric Co., Ltd., Moriguchi Akustischer Oberflächenwellenfilter
US5948981A (en) * 1996-05-21 1999-09-07 Alliedsignal Inc. Vibrating beam accelerometer
US6745627B1 (en) 1996-05-21 2004-06-08 Honeywell International Inc. Electrostatic drive for accelerometer
DE19636075A1 (de) * 1996-09-05 1998-03-19 Siemens Ag Mit akustischen Oberflächenwellen arbeitendes Filter -OFW-Filter-
JP3330512B2 (ja) * 1997-04-17 2002-09-30 株式会社日立製作所 弾性表面波素子
US5948982A (en) * 1998-02-23 1999-09-07 Alliedsignal Inc. Vibrating beam accelerometers and methods of forming vibrating beam accelerometers
NO984653L (no) * 1998-10-05 2000-04-06 Alsthom Cge Alcatel Overflateakustisk bølgetransduser
US6246150B1 (en) * 1999-10-28 2001-06-12 Kabushiki Kaisha Toshiba Surface acoustic wave device
US6791236B1 (en) 2000-10-11 2004-09-14 Yuri Abramov Method utilizing the saw velocity dispersion effect for weighting by shaping the electrode fingers of a saw interdigital transducer and apparatus produced thereby
DE10111959B4 (de) * 2001-03-13 2014-11-20 Epcos Ag Mit akustischen Wellen arbeitende Wandlerstruktur
CN204615783U (zh) * 2012-08-29 2015-09-02 株式会社村田制作所 弹性波装置以及滤波器装置

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3680007A (en) * 1970-09-30 1972-07-25 Ibm Surface wave transducer for digital signals
DE2431619A1 (de) * 1974-07-02 1976-01-22 Fraunhofer Ges Forschung Schallwandler fuer akustische oberflaechenwellen
JPS547257A (en) * 1977-06-20 1979-01-19 Hitachi Ltd Elastic surface wave device
US4162465A (en) * 1977-09-14 1979-07-24 University Of Illinois Foundation Surface acoustic wave device with reflection suppression
DE2839851C2 (de) * 1978-09-13 1980-09-25 Siemens Ag, 1000 Berlin Und 8000 Muenchen Oberflächenwellenanordnung mit verbesserter Störsignalunterdrückung
JPS5725714A (en) * 1980-07-23 1982-02-10 Oki Electric Ind Co Ltd Elastic surface wave converter
DE3208252A1 (de) * 1982-03-08 1983-09-15 Siemens AG, 1000 Berlin und 8000 München Interdigitalwandler mit unterdrueckung reflektierter stoersignale
JPS58191513A (ja) * 1982-05-06 1983-11-08 Toshiba Corp 弾性表面波素子
GB2132048A (en) * 1982-09-15 1984-06-27 Philips Electronic Associated Acoustic surface wave device
JPS61154212A (ja) * 1984-12-26 1986-07-12 Murata Mfg Co Ltd 弾性表面波フイルタ
DE3529916A1 (de) * 1985-08-21 1987-02-26 Siemens Ag Dispersiver interdigital-wandler fuer mit akustischen wellen arbeitenden anordnungen
JPH029213A (ja) * 1988-06-27 1990-01-12 Toshiba Corp 弾性表面波フィルタ

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9115897A1 *

Also Published As

Publication number Publication date
DE4010310A1 (de) 1991-10-02
WO1991015897A1 (fr) 1991-10-17
US5304965A (en) 1994-04-19
JPH05505081A (ja) 1993-07-29

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