EP0172811A1 - Filtre d'ondes acoustiques en surface ayant une configuration triangulaire - Google Patents

Filtre d'ondes acoustiques en surface ayant une configuration triangulaire

Info

Publication number
EP0172811A1
EP0172811A1 EP84901459A EP84901459A EP0172811A1 EP 0172811 A1 EP0172811 A1 EP 0172811A1 EP 84901459 A EP84901459 A EP 84901459A EP 84901459 A EP84901459 A EP 84901459A EP 0172811 A1 EP0172811 A1 EP 0172811A1
Authority
EP
European Patent Office
Prior art keywords
substrate
acoustic wave
surface acoustic
wave filter
reflector
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
Application number
EP84901459A
Other languages
German (de)
English (en)
Other versions
EP0172811A4 (fr
Inventor
Pol Buckinx
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.)
Osram Sylvania Inc
Original Assignee
GTE Products 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 GTE Products Corp filed Critical GTE Products Corp
Publication of EP0172811A1 publication Critical patent/EP0172811A1/fr
Publication of EP0172811A4 publication Critical patent/EP0172811A4/fr
Pending 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 devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02543—Characteristics of substrate, e.g. cutting angles
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; 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
    • H03H9/0285—Means for compensation or elimination of undesirable effects of reflections of triple transit echo

Definitions

  • This invention relates to surface wave acoustic de- vices and, more particularly, to an improved configuration for a filter substrate.
  • SAW surface wave acoustic
  • an input transducer in the form of a series of interdigitated conductive elements.
  • a similarly arranged output tranducer also in ⁇ cluding a series of interdigitated conductive elements.
  • a multi-strip coupler and a reflector are also included in the filter. The coupler causes signals launched by the transducer to be directed in quadrature to both the output transducer and the reflector. The phase relationship between the signals directed to the output transducer and the reflector results in substantial cancellation of "triple-transit" signals as thoroughly described in cited the patent. This is a highly desirable effect because
  • SAW filter incorporating dummy transducers and an absorptive coating so as to similarly reduce reflections and enhance the filter frequency response.
  • U.S. Patent 4,247,835 to Lewis depicts in Figure 1 a quartz crystal with various flat surfaces (that is, rhombohedral faces) lying in respective planes rotated about the crystal axes.
  • the various planes, or "cuts" are distinquishable in that each may be characterized as providing resonators whose individual natural operating frequencies vary as a function of temperature in a predetermined, predictable fashion.
  • the crystal cuts comprise a variety of irregularly perimetered surfaces.
  • the subject invention is directed t an improved triangular substrate configuration that not onl attenuates the level of reflected signals but also significantly reduces the amount of substrate material required.
  • the reduction in substrate surface area results • in a substantial reduction in the total cost of the device, largely because of the expense of the niobium component of, for example, a lithium niobate substrate.
  • the invention is a surface wave acoustic filter com ⁇ prising aluminum transducers deposited on a triangularly configured lithium niobate substrate.
  • the length of the sides of the substrate assume values eq ⁇ k-rst approximately 6.05, 9.25 and 11.05 milli ⁇ meters respectively.
  • the sole drawing is a pictorial representation of the subject SAW filter.
  • the subject surface wave acoustic filter includes, inter alia, a triangular substrate 1, which, in a preferred embodiment, is constructed from a piezoelectric material such as lithium niobate. Deposited on the substrate are an input transducer 5, an output transducer 2, a reflector 3 and a 3db coupler 4.
  • the above elements are typically constructed from an electrically conductive material such as aluminum. The specific operation and configuration are
  • the filter substrate is triangularly configured and comprises first, second and third sides 11, 12 and 13, respectively.
  • the second side has a nominal dimension F, of 9.25 millimeters (mm).
  • the third side of the substrate forms an angle, alpha, with an imaginary line that is perpendicular to the second side and has a length, J, nominally equal to 5.75 mm.
  • alpha has a nominal value of 18 degrees. From the above it can be demonstrated that the nominal lengths of sides 11, 12 and 13 (given the nominal value of alpha) are 11.05, 9.25 and 6.05 mm respectively.
  • the length, F, of the second side 12 may vary from 7 to 12 millimeters, the dimension J may vary from 3.0 to 10.0 mm, and the angle alpha may vary from 0 degrees to 36 degrees.
  • the first side of the substrate may vary from approximately 7.6 to 17.2 mm, the second side from 7.0 to 12.0 mm, and the third side from 3.0 to 12.3 mm respectively.
  • the thickness of the substrate may vary from approximately 0.1 to 1.0 mm, and again, may typically be constructed from lithium niobate, although other piezoelectric materials are certainly comtemplated by this invention.
  • the input transducer 5 has -an eight-sided perimeter, four sides
  • the reflector 3 has two sides 31 and 33 substantially parallel to the second side,- a side 32 substantially perpendicular to it and a side 34 substantially parallel to the third side.
  • the 3db coupler has a side 41 substantially parallel to the second side, sides 42 and 44 substantially perpendicu ⁇ lar to it, and a side 43 substantially parallel to the first side.
  • the relevant dimensions of the substrate, input and output transducers, 3db coupler and filter may be derived from the drawing and the table included therein. In practice those dimensions may vary, in millimeters, as follows:
  • the triangularly configured substrate exhibits at least two salient advantages.
  • the surface area of the substrate is the same.
  • OMPI may be estimated at approximately one-half of the substrate required in other known structures.
  • the surface wave reflections from the output transducer, and therefore the triple-transit reflections, are substantially reduced as a result of the triangular configura ion.
  • the subject invention is useful as a signal process- n ing device in various types of electronic equipment and, i particular, as a surface acoustic wave filter for tele ⁇ vision receivers.

Landscapes

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

Abstract

Un filtre d'ondes acoustiques en surface comprend un transducteur d'entrée en aluminium (5), un transducteur de sortie en aluminium (2), un coupleur 3db en aluminium (4), un réflecteur en aluminium (3), et un substrat de configuration triangulaire (1) construit à partir de niobate de lithium. Dans une configuration spécifique, les longueurs des côtés du substrat sont égales à 6,06, 9,25 et 11,05 millimètres respectivement, approximativement. La configuration triangulaire non seulement réduit la quantité nécessaire de matériau du substrat mais également atténue le degré de réflexion du signal "triple-transit" rencontrée.
EP19840901459 1984-02-21 1984-02-21 Filtre d'ondes acoustiques en surface ayant une configuration triangulaire. Pending EP0172811A4 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1984/000248 WO1985003816A1 (fr) 1984-02-21 1984-02-21 Filtre d'ondes acoustiques en surface ayant une configuration triangulaire

Publications (2)

Publication Number Publication Date
EP0172811A1 true EP0172811A1 (fr) 1986-03-05
EP0172811A4 EP0172811A4 (fr) 1987-01-10

Family

ID=22182053

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19840901459 Pending EP0172811A4 (fr) 1984-02-21 1984-02-21 Filtre d'ondes acoustiques en surface ayant une configuration triangulaire.

Country Status (2)

Country Link
EP (1) EP0172811A4 (fr)
WO (1) WO1985003816A1 (fr)

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1982003511A1 (fr) * 1981-04-06 1982-10-14 Prod Corp Gte Filtre d'ondes acoustiques de surface
WO1983002204A1 (fr) * 1981-12-14 1983-06-23 Gte Prod Corp Cire acoustique sur un dispositif a ondes de surface

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4146851A (en) * 1977-06-23 1979-03-27 Gte Laboratories Incorporated Acoustic surface wave device
GB2026804B (en) * 1978-05-24 1982-09-08 Secr Defence Surface acoustic wave devices
JPS56134819A (en) * 1980-03-25 1981-10-21 Toshiba Corp Surface wave filter

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1982003511A1 (fr) * 1981-04-06 1982-10-14 Prod Corp Gte Filtre d'ondes acoustiques de surface
WO1983002204A1 (fr) * 1981-12-14 1983-06-23 Gte Prod Corp Cire acoustique sur un dispositif a ondes de surface

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO8503816A1 *

Also Published As

Publication number Publication date
EP0172811A4 (fr) 1987-01-10
WO1985003816A1 (fr) 1985-08-29

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Legal Events

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Effective date: 19860221

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Effective date: 19870110

17Q First examination report despatched

Effective date: 19870525

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RIN1 Information on inventor provided before grant (corrected)

Inventor name: BUCKINX, POL