Surface acoustic wave transducer

Claim 2

A surface acoustic wave device comprising: a. a substrate having at least a piezoelectric layer thereon; and b. transducer means constructed for establishing predetermined centers of acoustic wave reflection on said substrate and selectively positionable on said substrate for causing acoustic wave propagation in said substrate in a predetermined orientation for establishing centers of transduction at any predetermined wave phase separation from said centers of reflection in a continuum of achievable phase angles within the range of 0°-360°.

Claim 3

A surface acoustic wave device as in Claim 1 wherein said transducer means for establishing said reflection centers comprises: a. at least first and second opposing electrical pads, and b. at least one electrode in interdigitated relationship depending from each of said at least first and second pads to define a transducer structure.

Claim 4

A surface acoustic wave device as in Claim 2 wherein said transducer is locally symmetrical in construction with electrodes at least a portion of which are one-quarter wave length whereby unidirectional transmission of acoustic waves from said transducer occurs when the wave separation of said centers of reflection and transduction is approximately +45° or ±135°.

Claim 5

A surface acoustic wave device comprising: a. at least one transducer having electrodes at least a portion of which are essentially two electrodes per wave length, and b. means for forming a unidirectional wave propagating device by selectively positioning said transducer on a piezoelectric crystal substrate having a prescribed crystal orientation so as to cause a wave propagation in a predetermined orientation in said substrate.

Claim 6

A surface acoustic wave device comprising: a. at least one transducer having electrodes at least a portion of which are essentially two electrodes per wave length, and b. means for forming a unidirectional wave propagating device by selectively positioning said transducer on a piezoelectric crystal substrate having a prescribed crystal orientation so as to cause a wave propagation in a predetermined orientation in said substrate.

Claim 7

A surface acoustic wave device as in Claim 4 wherein said transducer comprises: a. at least first and second opposing electrical pads, and b. at least one electrode extending from each of said first and second pads in interdigitated relationship to define a transducer structure.

Claim 8

A surface acoustic wave device as in Claim 5 wherein said means for forming said unidirectional wave propagating device comprises: a. said transducer electrodes establishing centers of wave reflection at predetermined locations on said substrate, and b. means for selectively positioning said transducer on said substrate to cause acoustic wave propagation in said substrate in such an orientation as to create centers of transduction in desired locations with respect to said centers of reflection.

Claim 9

A surface acoustic wave device as in Claim 6 wherein said means for selectively positioning said transducer on said crystal substrate includes: a. means for selecting said particular crystal cut and desired acoustic wave propagation direction on said crystal cut, and b. means for orienting said transducer on said crystal cut to obtain said acoustic wave propagation in said desired orientation.

Claim 10

A surface acoustic wave device comprising: a. a piezoelectric crystal substrate of specific cut in which centers of wave reflection and centers of transduction are established, b. at least one transducer constructed with localized symmetry and having electrodes thereon, c. an electrical load attached to said transducer, and d. means for selectively positioning said transducer on said substrate for causing wave propagation in said substrate in an orientation to thereby shift the phase location of said centers of transduction to a predetermined phase location with respect to said centers of reflection.

Claim 11

A surface acoustic wave device comprising: a. a piezoelectric crystal substrate of specific cut in which centers of wave reflection and centers of transduction are established, b. at least one transducer constructed with localized symmetry and having electrodes thereon, c. an electrical load attached to said transducer, and d. means for selectively positioning said transducer on said substrate for causing wave propagation in said substrate in an orientation to thereby shift the phase location of said centers of transduction to a predetermined phase location with respect to said centers of reflection.

Claim 12

A surface acoustic wave device as in Claim 8 wherein said phase location shift of said centers of transduction with respect to said centers of reflection comprises a phase angle continuum included in the range of 0°-360°.

Claim 13

In a surface acoustic wave device comprising a piezoelectric substrate, at least one transducer electrode pair on said substrate, an electrical load attached to said transducer electrode pair, an electrical input signal coupled to said electrode pair for generating surface acoustic waves in said substrate and having centers of wave reflection established on said substrate, the improvement comprising: a. means for forming said transducer with said at least one pair of electrodes being of 1/4 wavelength, and b. means for causing acoustic wave propagation in a desired orientation in said substrate so as to cause said transducer to be unidirectional by selectively positioning said transducer on said substrate.

Claim 14

In a surface acoustic wave device comprising a piezoelectric substrate, at least one transducer electrode pair on said substrate, an electrical load attached to said transducer electrode pair, an electrical input signal coupled to said electrode pair for generating surface acoustic waves in said substrate and having centers of wave reflection established on said substrate, the improvement comprising: a. means for forming said transducer with said at least one pair of electrodes being of 1/4 wavelength, and b. means for causing acoustic wave propagation in a desired orientation in said substrate so as to cause said transducer to be unidirectional by selectively positioning said transducer on said substrate.

Claim 15

An improved surface acoustic wave device as in Claim 10 wherein said means for causing said transducer to be unidirectional comprises selectively positioning said transducer on said substrate to cause wave propagation in an orientation in said substrate for establishing centers of transduction separated from centers of reflection by a desired phase separation to minimize acoustical reflection on the desired acoustic port under specified loading conditions.

Claim 16

A surface acoustic wave device comprising: a. a piezoelectric substrate, b. at least one transducer having electrodes with localized symmetry and establishing centers of wave reflection and transduction with respect to said electrodes, said transducer being positioned on said substrate such that wave propagation through said substrate is in an orientation to cause said centers of transduction to be positioned at desired locations with respect to said centers of reflection; and c. an electrical load attached to said transducer.

Claim 17

A surface acoustic wave device comprising: a. a piezoelectric substrate, b. at least one transducer having electrodes with localized symmetry and establishing centers of wave reflection and transduction with respect to said electrodes, said transducer being positioned on said substrate such that wave propagation through said substrate is in an orientation to cause said centers of transduction to be positioned at desired locations with respect to said centers of reflection; and c. an electrical load attached to said transducer.

Claim 20

A method as in Claim 13 wherein said step of establishing said reflection centers comprises: a. forming at least first and second opposing electrical pads, and b. attaching at least one electrode to each of said first and second pads in interdigital relationship to define a transducer structure.

Claim 21

A method as in Claim 14 wherein the step of obtaining said desired wave phase separation further comprises the steps of: a. determining the location of desired centers of transduction in phase relation to said centers of reflection, and b. creating centers of transduction in desired locations to obtain said desired wave phase separation by selectively positioning said transducer on said substrate to cause acoustic wave propagation in said substrate in a desired orientation.

Claim 22

A method as in Claim 15 wherein said step of creating said centers of transduction includes attachment of said transducer to said substrate with respect to desired Euler angles thereby enabling said centers of transduction to be located in a predetermined phase relationship with respect to said centers of reflection throughout a predetermined achievable range of 0°-360° phase separation.

Claim 23

A method as in Claim 16 further including the step of constructing said transducer in a symmetrical form with only one-quarter wave length electrodes whereby unidirectional transmission of acoustic waves from said transducer occurs when the wave separation of said centers of reflection and transduction is at +45° or +135°.

Claim 26

A method as in Claim 18 wherein said step of constructing said transducer comprises the steps of: a. forming at least first and second opposing electrical pads, and b. extending at least one electrode from each of said first and second pads in interdigitated relationship to define said transducer structure.

Claim 27

A method as in Claim 19 further including the steps of: a. forming predetermined centers of wave reflection in said crystal based upon said transducer electrode structure, b. determining the location of desired centers of transduction in said crystal in relation to said centers of reflection, and c. creating said centers of transduction in said desired locations by selectively orienting said transducer on said crystal cut.

Claim 28

A method as in Claim 20 further comprising the step of selectively orienting said transducer on said substrate cut at a predetermined Euler angle thereby enabling said centers of transduction to be varied with respect to said centers of reflection throughout the achievable range of 0°-360° phase separation.

Claim 31

A method of forming a surface acoustic wave device as in Claim 22 wherein the step of shifting the phase locations of said centers of transduction further comprises the step of shifting said phase locations of said centers of transduction with respect to said centers of reflection through an achievable phase angle continuum within the range of 0°-360°.

Claim 32

In a method for constructing a surface acoustic wave device having a piezoelectric substrate, at least one transducer electrode pair on said substrate, an electrical load attached to said transducer electrode pair, an electrical input coupled to said electrode pair for generating surface acoustic waves in said substrate and having centers of wave reflection on said substrate, the improvement comprising the steps of: a. selecting a specific cut of a piezoelectrical crystal, b. forming said transducer with said at least one pair of electrodes separated approximately by 1/2 wavelength, and c. causing said transducer to be unidirectional by selectively positioning said transducer on said crystal cut in a specific direction.

Claim 33

In a method for constructing a surface acoustic wave device having a piezoelectric substrate, at least one transducer electrode pair on said substrate, an electrical load attached to said transducer electrode pair, an electrical input coupled to said electrode pair for generating surface acoustic waves in said substrate and having centers of wave reflection on said substrate, the improvement comprising the steps of: a. selecting a specific cut of a piezoelectrical crystal, b. forming said transducer with said at least one pair of electrodes separated approximately by 1/2 wavelength, and c. causing said transducer to be unidirectional by selectively positioning said transducer on said crystal cut in a specific direction.

Claim 34

A method as in Claim 24 wherein the step of causing said transducer to be unidirectional further comprises the step of causing wave propagation in a predetermined orientation in said crystal for establishing centers of transduction separated from said centers of reflection by ±45° phase separation or +135° phase separation thereby creating a unidirectional transmission of said acoustic waves By said transducer.

Claim 35

An improved method of forming a SAW device having a piezoelectric substrate, at least one transducer having at least one pair of electrodes with localized symmetry and being mounted on said substrate such that centers of wave reflection are established with respect to said electrodes, and an electrical load attached to said transducer, the improvement comprising the steps of: a, selecting predetermined desired phase locations for centers of transduction with respect to said centers of reflection, b. selecting a specific cut of said piezoelectrical crystal, and c. causing said centers of transduction to be positioned at said desired phase locations with respect to said centers of reflection by selectively positioning said transducer on said crystal cut such that wave propagation through said substrate is in a predetermined orientation.

Claim 36

An improved method of forming a SAW device having a piezoelectric substrate, at least one transducer having at least one pair of electrodes with localized symmetry and being mounted on said substrate such that centers of wave reflection are established with respect to said electrodes, and an electrical load attached to said transducer, the improvement comprising the steps of: a, selecting predetermined desired phase locations for centers of transduction with respect to said centers of reflection, b. selecting a specific cut of said piezoelectrical crystal, and c. causing said centers of transduction to be positioned at said desired phase locations with respect to said centers of reflection by selectively positioning said transducer on said crystal cut such that wave propagation through said substrate is in a predetermined orientation.

Claim 37

A surface acoustic wave device for minimizing triple transit distortion in a surface acoustic wave filter comprising: a. a piezoelectric substrate, b. first and second transducers each having at least one pair of electrodes separated by approximately 1/2 wavelength, c. an electrical load coupled to each of said first and second transducers, d. means for selectively positioning said first and second transducers on said substrate to cause acoustic wave propagation in said substrate in such an orientation so as to create unidirectional transmission of said acoustic waves in said substrate to thereby minimize acoustic reflections between said transducers, and e. means for forming said electrodes of a particular metal to obtain unidirectional transmission in said device.

Claim 38

A surface acoustic wave device for minimizing triple transit distortion in a surface acoustic wave filter comprising: a. a piezoelectric substrate, b. first and second transducers each having at least one pair of electrodes separated by approximately 1/2 wavelength, c. an electrical load coupled to each of said first and second transducers, d. means for selectively positioning said first and second transducers on said substrate to cause acoustic wave propagation in said substrate in such an orientation so as to create unidirectional transmission of said acoustic waves in said substrate to thereby minimize acoustic reflections between said transducers, and e. means for forming said electrodes of a particular metal to obtain unidirectional transmission in said device.

Claim 39

A SAW device as in Claim 27 wherein said means for selective positioning said transducers further comprises: a. means for establishing centers of reflection and transduction, and b. means for controlling the phase separation of said centers of transduction with respect to said centers of reflection to thereby obtain opposing unidirectionality of said transducers and minimization of triple transit reflections between said transducers,

Claim 40

A device as in Claim 28 wherein at least one of said transducers is unidirectional in the direction of the other transducer.