Voltage stress stabilized saw device
AssigneeInternational Telephone and Telegraph Corporation
InventorRobert M. Woskow
Life of this patent
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Abstract
An oscillator or similar device employing a frequency setting SAW element having a piezoelectric substrate and an arrangement of interdigital finger transducers mounted thereon. In one embodiment, two interdigital finger transducers provide surface acoustic wave launching and reception respectively and in another embodiment, two additional transducers form a part of a discriminator circuit. Phase detection either between the electrical connections of the launching and receiving transducers or through the discriminator arrangement generates a feedback control signal which is applied across the ends of the substrate as a stress-controlling signal in a manner to compensate for temperature and other environmental factors which otherwise change the frequency of oscillation.
Claims10
A device such as an oscillator, having a surface acoustic wave frequency determining element, comprising:
- a substrate of piezoelectric material having a planar surface;
- first and second transducers each having interleaved interdigital finger transducers affixed to said planar surface for launching and receiving surface acoustic waves on said planar surface, respectively;
- phase detecting means connected to monitor said surface acoustic waves and to generate a control signal as a function of a change of wavelength of said acoustic waves on said planar surface;
- and means for applying said control signal as a stress-inducing signal producing a potential gradient within said substrate in the direction of propagation of said surface waves, said control signal being applied in a sense tending to compensate for said changes of wavelength of said acoustic waves.
Dependencies are inferred from the claim text.