Linear voltage-controlled oscillator using fixed capacitors in lieu of varactors
AssigneeAT&T Corp.
InventorIrving G. Post
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Abstract
The frequency of a resonant circuit in the emitter path of an output transistor is caused to vary linearly with control voltage. The control voltage is applied to a circuit that constrains the ac current through the resonant circuit to be supplied through the emitters of a two-transistor current steering circuit. The sum of the two transistor's dc emitter currents is constant while the dc current through one of the two transistors' emitters varies as the square root of the control voltage.
Claims10
A voltage-controlled oscillator comprising a series resonant circuit and a control circuit employing transistors, fixed capacitors and no varactors for varying the effective amount of capacitance present in said resonant circuit so that the resonant frequency varies substantially linearly with control voltage.
A voltage-controlled oscillator comprising a series resonant circuit and a control circuit in which said control circuit includes a two-transistor circuit for driving said resonant circuit and a current supply circuit for controlling the relative amount of current through the transistors of said two-transistor circuit as a control voltage is varied.
A voltage-controlled oscillator circuit including a resonant circuit in the emitter path of an output transistor comprising
- a two-transistor feedback circuit coupled to said output transistor,
- means for controlling the current through said two-transistor circuit so that the sum of the two transistors' dc emitter currents is constant, and
- means for controlling the dc current through one of the two transistors' emitters to vary as the square root of a control voltage.
Dependencies are inferred from the claim text.