Crystal oscillator
AssigneeNorthern Telecom Limited
InventorGeorge H. S. Rokos
Life of this patent
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Abstract
A tuneable crystal oscillator arrangement includes a piezo-electric, e.g. quartz, crystal and drive current means therefor. A reactance is arranged in series with the crystal and is fed with a current corresponding to the crystal drive current. The corresponding voltage developed across the impedance is fed via a variable gain amplifier back to the crystal. The reactance comprises a number of impedances, there being current steering means for dividing the current between the impedances. This determines the effective value of the reactance and provides a control or adjustment of the crystal frequency.
Claims6
A frequency tuneable crystal oscillator arrangement, including a piezo-electric crystal, means for providing a drive current to the crystal, a reactance into which a current corresponding to the crystal current is fed whereby to develop a corresponding voltage across that reactance, and an adjustable gain amplifier for amplifying said voltage and for feeding said amplified voltage back to the crystal, wherein said reactance is arranged in series with the crystal, and wherein the reactance comprises a plurality of different impedances, there being current steering means for dividing the current corresponding to the crystal current between the impedances whereby to determine the effective value of the reactance in series with the crystal whereby to control the crystal frequency.
Dependencies are inferred from the claim text.