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US 4,782,309 AGranted
Bilateral frequency adjustment of crystal oscillators
AssigneeThe United States of America as represented by the Secretary of the Army
InventorAlbert Benjaminson
Life of this patent
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Abstract
A crystal oscillator in a bridge circuit coupled to a differential amplifier. Coordinated adjustment of one or two arms of the bridge permits pulling of the crystal's operating frequency both above and below its series resonant frequency.
Claims8
An oscillator circuit comprising:
- a bridge circuit including a first pair of first and second connected arms, each having an impedance reactance means and a second pair of connected arms, the first arm of said second pair having a piezoelectric crystal connected in series with a capacitive reactance means, and the second arm of said second pair having a capacitive reactance means connected in series with a resistor;
- a differential amplifier having an inverting input and a non-inverting input, said non-inverting input being connected between said first pair of arms and said inverting input being connected between said second pair of arms, the output of said amplifier being connected between said second arm of said second pair and said second arm of said first pair.
Dependencies are inferred from the claim text.