High bulk mode rejection surface wave device
First Claim
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1. A surface wave device having substantially no bulk mode signal output comprising:
- a. a substrate for conveying acoustic waves;
b. a first transducer having a plurality of electrodes in operative association with the substrate for generating acoustic surface waves, each of said plurality of electrodes having a preselected spacing as to an adjacent electrode at one-half wavelength at a desired operating frequency to reduce substantially the response of the first transducer to bulk waves at the operating frequency; and
c. a second transducer having a plurality of electrodes in operative association with the substrate for receiving the first transducer output, each of said plurality of electrodes having preselected spacings from an adjacent electrode at one-half wavelength of a preselected subharmonic of said operating frequency.
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Abstract
Disclosed is a surface wave device comprising one transducer having its fundamental resonant frequency at a subharmonic of the device operating frequency and a second transducer having its fundamental resonant frequency at the device operating frequency. Both transducers respond to surface waves at the operating frequency. Only the harmonic operated transducer responds to bulk waves at the operating frequency. Thus, signal coupled from one transducer to the other at the operating frequency contains no noise generated by bulk mode coupling.
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Citations
6 Claims
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1. A surface wave device having substantially no bulk mode signal output comprising:
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a. a substrate for conveying acoustic waves; b. a first transducer having a plurality of electrodes in operative association with the substrate for generating acoustic surface waves, each of said plurality of electrodes having a preselected spacing as to an adjacent electrode at one-half wavelength at a desired operating frequency to reduce substantially the response of the first transducer to bulk waves at the operating frequency; and c. a second transducer having a plurality of electrodes in operative association with the substrate for receiving the first transducer output, each of said plurality of electrodes having preselected spacings from an adjacent electrode at one-half wavelength of a preselected subharmonic of said operating frequency. - View Dependent Claims (2, 3, 4, 5)
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6. A method for fabricating surface wave devices for substantially rejecting bulk mode signals comprising:
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a. forming electrodes with preselected spacings for an input surface wave transducer on a piezoelectric substrate for substantially reducing the response including bulk wave signal response of the transducer to a desired harmonic as to a fundamental resonant frequency; and b. forming electrodes with preselected spacings for an output transducer for covering a subharmonic of said fundamental resonant frequency;
whereby said transducers cooperate during operation to reject bulk wave signals at the desired harmonic and fundamental resonant frequency.
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Specification