EP1264397A1 - Convertisseur d'ondes de surface a reflexion optimisee - Google Patents

Convertisseur d'ondes de surface a reflexion optimisee

Info

Publication number
EP1264397A1
EP1264397A1 EP01913681A EP01913681A EP1264397A1 EP 1264397 A1 EP1264397 A1 EP 1264397A1 EP 01913681 A EP01913681 A EP 01913681A EP 01913681 A EP01913681 A EP 01913681A EP 1264397 A1 EP1264397 A1 EP 1264397A1
Authority
EP
European Patent Office
Prior art keywords
converter
finger
reflection
electrode fingers
cells
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.)
Withdrawn
Application number
EP01913681A
Other languages
German (de)
English (en)
Inventor
Andreas Bergmann
Jürgen Franz
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.)
TDK Electronics AG
Original Assignee
Epcos AG
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 Epcos AG filed Critical Epcos AG
Publication of EP1264397A1 publication Critical patent/EP1264397A1/fr
Withdrawn legal-status Critical Current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
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
    • 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
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
    • H03H9/14502—Surface acoustic wave [SAW] transducers for a particular purpose
    • H03H9/14505—Unidirectional SAW transducers
    • 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
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
    • H03H9/14517—Means for weighting
    • 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
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
    • H03H9/14517—Means for weighting
    • H03H9/14523—Capacitive tap weighted transducers

Definitions

  • the invention relates to an interdigital transducer for generating surface acoustic waves, in short surface wave transducers or in the following also generally called transducers.
  • a transducer usually consists of two comb-shaped electrodes, each called a current busbar or busbar and comprising electrode fingers attached to it. Two such interdigitated electrode combs form an interdigital transducer.
  • a surface wave filter can be constructed, for example, from a piezoelectric substrate with two interdigital transducers serving as input and output transducers. The acoustic generated in the input converter
  • the path of the surface acoustic wave which may be limited on both sides of the transducers by reflectors or may extend into them, is also referred to as the acoustic track.
  • the efficiency of the electro-acoustic conversion is optimal at the center frequency.
  • the filter is set so that it has good pass behavior over a desired bandwidth in the vicinity of its center frequency. Within this band, a filter should have the lowest possible insertion loss, that is to say a low loss in the coupling and transmission of the surface wave. Signals outside this band should be attenuated in the filter.
  • a narrow band filter can be obtained by increasing the number of electrode fingers so that a long transducer is obtained.
  • each electrode finger of the normal finger transducer is replaced by two split fingers arranged at a distance of ⁇ / 4, which are mechanically reflection-free, since the reflections of the two fingers cancel each other out.
  • problems can also arise here in the case of longer transducers, so that a split transducer transducer is not free of reflection due to the electrical regeneration at the non-zero terminating impedance at the acoustic gates
  • a reflective electrode finger is arranged in a unit line of length ⁇ st, over whose width and exact position the reflection of this cell can be adjusted. In this way it is possible to model a transducer that has a desired reflection distributed across the transducer. This distributed reflection can follow a weighting, for example.
  • a transducer according to the invention is made up of a number of basic cells arranged in a row in the direction of propagation of the surface wave, all of which have the approximate length ⁇ , where ⁇ represents the center frequency of the transducer.
  • the transducer can be divided into stimulating and reflecting base cells to which the reflection contribution has only certain values mx R 0 , where m can take the values -2, -1, 0, 1 or 2, and where R 0 is a reference reflection.
  • Each of 0 different reflection contributions has the same phase position ⁇ O.
  • the phase position and excitation strength like the number of stimulating fingers, are identical in all stimulating basic cells.
  • the phase relationship between excitation and reflection leads to the unidirectional behavior of the transducer, with phase alignment being obtained in one preferred direction, but phase opposition in the opposite direction.
  • a transducer according to the invention is no longer subdivided strictly into stimulating and reflecting fingers; rather, stimulating fingers also have a contribution to reflection which is optimized to the desired phase position and strength by varying the finger width and finger position. This can also increase the unidirectionality of the converter, which in a filter with such a converter leads to reduced insertion loss, a longer impulse response and steeper flanks of the passband of the pass curve.
  • the stimulating base cells of a transducer according to the invention can all have exactly one electrode finger individually connected to a busbar as a stimulating electrode.
  • a transducer in which the finger widths and spacings of the electrode fingers increase or decrease continuously in the transverse direction (transverse to the direction of propagation of the surface wave). Such a measure increases the bandwidth of a converter and thus also the bandwidth of a filter in which the converter according to the invention is used.
  • the transducer is designed to focus and has electrode fingers with curved edges.
  • Such a transducer has the advantage that, when used as an input transducer in a surface acoustic wave filter, the scattering losses are reduced, since the focusing also means that those surface waves still get into the receiving and output transducers that can no longer reach the input transducer with electrode fingers that are running would. This also lowers the insertion loss of the converter or filter.
  • all finger widths and all finger spacings of the electrode fingers are different in each basic cell. This means that a certain finger width or a certain finger distance occurs at most once within a basic cell.
  • this is preferably, but not exclusively, used in an IF filter which, with the invention, has a low insertion loss and, due to the additionally created resonance spaces, an extended impulse response.
  • FIGS. 2a to c show different types of double finger cells
  • FIG. 3 shows an exemplary basic cell according to the invention
  • the precise determination of the finger geometries, in particular the finger widths and the finger distances, is carried out by formulating a solvable optimization task.
  • Optimization methods for transducers are already known, but these are subject to restrictions, so that the cells to be constructed have fewer degrees of freedom than the geometry widths available.
  • the problem can be generalized for an optimization method for producing transducers according to the invention, so that the restrictions applicable to previous optimization methods, in particular the fixed relationships of finger widths and positions, are eliminated.
  • the reflection of a cell could only be adjusted by the metallization height.
  • a continuous width variation of the reflection finger or fingers is now possible.
  • the geometries without excitation are formed directly from the geometries with excitation by omitting the overlap, for example by changing the finger connection sequence.
  • the basic cells from known single and double finger cells are selected as the starting geometries for the optimization task.
  • Figures la to c show three different approaches for single finger cells, in which only one electrode finger is arranged on the signal-carrying busbar.
  • the Single finger cells can be composed of three or four electrode fingers.
  • FIG. 1 a shows a single-use cell without reflection that can be used as a starting point and has a regular ⁇ / 8 finger arrangement in the ⁇ / 8 grid, which is reflection-free in the event of an electrical short circuit.
  • FIG. 1c shows how a single finger cell with negative reflection is created from this cell by exchanging two electrode fingers.
  • the phase difference of the reflection between cells with positive and cells with negative reflection is 90 °, so that the phase difference of the reflection at the transducer ends of these simple transducers is 180 °.
  • FIGS. 2a to c show different types of double finger cells, in each of which two electrode fingers are connected to the signal-carrying busbar.
  • FIG. 2a again shows a regular ⁇ / 8 finger arrangement that is reflection-free.
  • FIG. 2b shows a double finger cell with positive reflection
  • Figure 2c shows a double finger cell with negative reflection.
  • the known and known single and double cell cells serve as the starting point for the optimization. If a converter is electrically connected, i.e. connected to an external load, acoustic-electrical feedback M iV) 1

Landscapes

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

Abstract

La présente invention concerne un convertisseur pour filtre à convertisseur d'ondes de surface, à pouvoir de réflexion optimisé. Ce convertisseur présente un perte d'insertion peu élevée, une grande sélectivité et une unidirectivité maximale. Selon cette invention, les cellules de base d'excitation et/ou de réflexion du convertisseur sont optimisées. Chaque cellule de base d'excitation apporte la même contribution d'excitation et chaque cellule de base de réflexion apporte le multiple entier d'une réflexion de référence.
EP01913681A 2000-03-02 2001-02-19 Convertisseur d'ondes de surface a reflexion optimisee Withdrawn EP1264397A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10010089A DE10010089A1 (de) 2000-03-02 2000-03-02 Oberflächenwellenwandler mit optimierter Reflexion
DE10010089 2000-03-02
PCT/DE2001/000630 WO2001065688A1 (fr) 2000-03-02 2001-02-19 Convertisseur d'ondes de surface a reflexion optimisee

Publications (1)

Publication Number Publication Date
EP1264397A1 true EP1264397A1 (fr) 2002-12-11

Family

ID=7633184

Family Applications (1)

Application Number Title Priority Date Filing Date
EP01913681A Withdrawn EP1264397A1 (fr) 2000-03-02 2001-02-19 Convertisseur d'ondes de surface a reflexion optimisee

Country Status (8)

Country Link
US (1) US6777855B2 (fr)
EP (1) EP1264397A1 (fr)
JP (1) JP2003526240A (fr)
KR (1) KR100752828B1 (fr)
CN (1) CN1190893C (fr)
CA (1) CA2400719A1 (fr)
DE (1) DE10010089A1 (fr)
WO (1) WO2001065688A1 (fr)

Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3414373B2 (ja) * 2000-07-26 2003-06-09 株式会社村田製作所 弾性表面波装置
JP3674564B2 (ja) * 2001-09-25 2005-07-20 セイコーエプソン株式会社 半導体装置およびその製造方法
JP3844725B2 (ja) * 2002-09-30 2006-11-15 富士通メディアデバイス株式会社 弾性表面波フィルタ、それを有する弾性表面波分波器
JP4302394B2 (ja) * 2002-12-02 2009-07-22 ポリプラスチックス株式会社 ポリオキシメチレン樹脂製延伸体の製造方法
US7096736B2 (en) * 2003-08-04 2006-08-29 The Goodyear Tire & Rubber Company Passive tire pressure sensor and method
DE10345239B4 (de) * 2003-09-29 2013-09-05 Epcos Ag Mit Oberflächenwellen arbeitender Wandler
DE102005009359B4 (de) * 2005-03-01 2014-12-11 Epcos Ag Bandpassfilter
DE102005045638B4 (de) * 2005-09-23 2017-02-02 Epcos Ag Mit Oberflächenwellen arbeitender Wandler
US8340768B2 (en) * 2007-12-12 2012-12-25 Cardiac Pacemakers, Inc. Sensing threshold control to limit amplitude tracking
US8436509B1 (en) 2008-07-08 2013-05-07 Saudia Corporation High-frequency shear-horizontal surface acoustic wave sensor
US7939989B2 (en) * 2009-09-22 2011-05-10 Triquint Semiconductor, Inc. Piston mode acoustic wave device and method providing a high coupling factor
US8294331B2 (en) 2009-09-22 2012-10-23 Triquint Semiconductor, Inc. Acoustic wave guide device and method for minimizing trimming effects and piston mode instabilities
DE102012107049B4 (de) 2012-08-01 2017-10-05 Snaptrack, Inc. Elektroakustischer Wandler
US10261078B2 (en) 2015-08-17 2019-04-16 National Technology & Engineering Solutions Of Sandia, Llc Shear horizontal surface acoustic wave (SH-SAW) resonators and arrays thereof
US10009002B1 (en) 2015-09-04 2018-06-26 National Technology & Engineering Solutions Of Sandia, Llc Methods for suppressing spurious modes in microresonators
US11405014B1 (en) 2019-06-27 2022-08-02 National Technology & Engineering Solutions Of Sandia, Llc Solid-state tuning behavior in acoustic resonators

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GB2078042B (en) * 1980-06-13 1984-08-08 Nippon Telegraph & Telephone Surface acoustic wave resonator
US4473888A (en) * 1981-10-28 1984-09-25 The United States Of America As Represented By The Secretary Of The Army Saw monolithic convolver using dispersive transducers
JPS58213519A (ja) * 1982-06-07 1983-12-12 Clarion Co Ltd 弾性表面波装置
US4910839A (en) * 1984-12-03 1990-03-27 R.F. Monolithics, Inc. Method of making a single phase unidirectional surface acoustic wave transducer
DE3529916A1 (de) * 1985-08-21 1987-02-26 Siemens Ag Dispersiver interdigital-wandler fuer mit akustischen wellen arbeitenden anordnungen
EP0255263B1 (fr) 1986-07-29 1995-01-04 R F Monolithics, Inc. Transducteur
US4918349A (en) * 1987-11-13 1990-04-17 Hitachi, Ltd. Surface acoustic wave device having apodized transducer provided with irregular pitch electrode group
JP2847438B2 (ja) * 1991-03-29 1999-01-20 三井金属鉱業株式会社 弾性表面波素子
US5793146A (en) * 1993-11-12 1998-08-11 Rf Monolithics, Inc. Surface acoustic wave transducer having selected reflectivity
US5818310A (en) * 1996-08-27 1998-10-06 Sawtek Inc. Series-block and line-width weighted saw filter device

Non-Patent Citations (1)

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Title
See references of WO0165688A1 *

Also Published As

Publication number Publication date
US6777855B2 (en) 2004-08-17
CA2400719A1 (fr) 2001-09-07
KR20020079927A (ko) 2002-10-19
WO2001065688A1 (fr) 2001-09-07
US20030057805A1 (en) 2003-03-27
KR100752828B1 (ko) 2007-08-29
CN1190893C (zh) 2005-02-23
CN1406412A (zh) 2003-03-26
JP2003526240A (ja) 2003-09-02
DE10010089A1 (de) 2001-09-06

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