Vectron International Gmbh & Co. Kg

Vectron International Gmbh

Leibniz-institut Fuer Festkoerper-und Werkstoffforschung Dresden E.v.

Tele Filter Zweigniederlassung Der Dover Germany, Gmbh

Leibniz-institut Fuer Festkoerper-und Werkstofforschung Dresden E.v.

Tele Filter Gmbh

Dover Europe Gmbh

Guenter Martin

Bert Wall

Manfred Weihnacht

Sergey Biryukov

Bernd Steiner

Alexander Darinski

A surface acoustic wave component contains two fan-shaped interdigital transducers disposed on a piezoelectric substrate, the prongs and gaps of which transducers forming groups having the same length, called cells, between them, and narrow in the averaged prong direction. The cells are structured like cells of unidirectional transducers, and at least one of the fan-shaped interdigital transducers is composed of partial transducers. The partial transducers are disposed one behind the other, perpendicular to the averaged prong direction.

Surface acoustic wave component

A surface wave component contains at least two interdigital transducers having natural unidirectionality, disposed on a piezoelectric crystal substrate, which form a transducer pair consisting of transmission transducer and reception transducer. The transducers consist of an interdigital electrode structure having prongs and bus bars, and have opposite forward directions. At least two of the prongs form a transducer cell that has at least one excitation center for exciting an electrical potential wave and at least one reflection center for reflection of electrical potential waves, The transducer cells consist of two prongs having the same width, having a distance between the prong centers equal to half the length of a transducer period, whereby the electrode structures of the two transducers consist of the same material, but have different layer thicknesses.

A transducer has natural unidirectionality for surface acoustic waves. An interdigital electrode structure is arranged on a piezoelectric crystal substrate and is constructed with interdigital transducers including collecting electrodes and fingers. At least two of the fingers form a transducer cell, which includes at least one excitation center for exciting an electrical potential wave and at least one reflection center for reflecting electrical potential waves. The fingers are oriented perpendicularly to a direction R parallel to a 1- or 3-fold rotational axis of the substrate crystal and the derivative dv/d&#x3b8;=0 applies to R, wherein v is the phase velocity of the surface wave and &#x3b8; is an angular deviation of the perpendicular to the finger direction from the direction R.

Transducer having natural unidirectionality for surface acoustic waves

The invention relates to waveguide components based on acoustic surface waves, comprising at least one interdigital converter for exciting acoustic surface waves in a piezoelectric substrate or a piezoelectric layer. The object of the invention is to change known waveguide components, comprising at least one interdigital converter for exciting acoustic surface waves in a piezoelectric substrate or a piezoelectric layer, such that no reflectors are necessary with an otherwise equivalent function. The inventive waveguide components are characterized in that the interdigital converter(s) a) is or are disposed at a defined distance over the piezoelectric substrate or the piezoelectric layer for exciting wave fields, or b) is or are in contact with the piezoelectric substrate or the piezoelectric layer, wherein in version a) the piezoelectric substrate is designed as a ring and the piezoelectric layer is designed as a circular region. In case of version b), the interdigital converter and/or the piezoelectric layer form circular regions. The components can be used for example as resonators, filters, oscillators and sensors.

Waveguide components on the basis of acoustic surface waves, and their use

A transducer for surface acoustic waves, and a resonator and a filter for surface acoustic waves having the transducer are provided. The transducer for surface acoustic waves has cells containing two electrode fingers per cell, wherein the transducer exhibits unidirectional behavior for propagation directions of the surface acoustic waves parallel to highly symmetrical directions of the crystal substrate. Each of two electrodes have a plurality of electrode fingers, the electrode fingers having center axes extending parallel to their longitudinal axes and being spaced apart from center axes of adjacent electrode fingers of the same electrode by a distance which equals the ratio of the velocity of the surface acoustic wave and the cut-off frequency of the transducer. The electrode fingers of both electrodes define a plurality of cells each consisting of two fingers.

Transducer for surface acoustic waves and a resonator and a filter having said transducer

An oscillator circuit includes a combination of two frequency-determining elements, designed as single-port surface wave resonators with interdigital converters, and one active electronic circuit. The two single-port surface wave resonators are connected to each other, avoiding inductive components. In the case of a combination in a parallel circuit, the connection is designed as a combination oscillating at high-frequency anti-resonance, and in the case of a combination in a series circuit, the combination is designed as a combination oscillating at high-frequency resonance. A ratio of apertures of the interdigital converters to one another, a ratio of their number of prongs to one another, and the thickness of the electrode layer of the single-port surface wave resonators as well as the propagation direction for acoustic surface waves of the single-port surface wave resonators are selected so that the temperature-dependent change of the phase of the combination and the temperature-dependent change of the total phase of the rest of the elements of the oscillator circuit have signs opposite to one another and that the sum of these phase changes in a thermal operating range of the oscillator circuit is smaller than a value of the phase change of the combination and smaller than a value of the phase change of the rest of the elements of the oscillator circuit.

Oscillator circuit with acoustic single-port surface wave resonators

An oscillator or a sensor comprising a unit including two frequency determining elements each of which comprises at least one interdigital converter for acoustic surface waves and a back-coupling circuit comprising an amplifier, wherein the frequency determining elements are distinguished by a temperature dependence of a synchronous frequency. The frequency determining elements are embodied in the form of acoustic surface wave resonators, and the temperature coefficients of n-th order of the synchronous frequency of the two acoustic surface wave resonators have different sings if they are not equal to zero and the temperature coefficients of (n+1st) order of the synchronous frequency of the two acoustic surface wave resonators have the same sign and the temperature coefficients from the first order to (n-1st) order of the synchronous frequency of the two acoustic surface wave resonators are equal to zero if n is greater than 1, wherein n being equal to or greater than 1, c) the ratio between the converter openings and the ratio between the lengths in the direction perpendicular to the edge teeth of the converter and to strips of the object reflectors having different frequency determining elements which are assembled in one unit are selected in such a way that the oscillator frequency variation is minimum within the range of given temperatures.

Oscillator with acoustic surface wave resonators

A resonator filter cascade has resonator structures disposed adjacent to one another and form a waveguide for acoustic surface waves, and coupling transducers. The present invention changes resonator filter cascades so that the insertion attenuation is reduced by decreasing the attenuation of cascading, without using a coupling coil. A resonator filter cascade has resonator structures having coupling transducers which transversely couple resonator filters and the coupling transducers, belonging the same transversely coupled resonator filter, are not connected with one another. Coupling transducers of different transversely coupled resonator filters are each connected with one another over a pair of electrically conducting connections.

Resonator filter cascade

An improvement of a surface acoustic wave component is disclosed. Surface acoustic wave components of the known type are changed in such a way that the dependency of the insertion loss and/or group delay time on the frequency as asymmetric function in relation to the center frequency can be realized in a predetermined manner. Sloping passbands are particularly significant in this respect. As disclosed, in a surface acoustic wave component in which two single-phase unidirectional transducers which are composed of finger groups comprising a pair of fingers and a reflection finger are arranged on a piezoelectric substrate, wherein the two fingers of the pair of fingers have opposite polarity and are at a distance of one quarter wavelength from one another, at least one base element in at least one of the single-phase unidirectional transducers differs from the rest of the base elements with respect to its distance between the center of the reflection finger and the center of the nearest finger of its pair of fingers. The device of the invention is applicable, for example, for bandpass filters with a relative bandwidth of up to several percent and for oscillators.

Growing community of inventors

Dresden, Germany

Guenter Martin