Voltage controlled oscillator employing negative resistance
AssigneeMotorola, Inc.
InventorsPhuc C. Pham, Carl Denig
Life of this patent
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Abstract
A voltage controlled oscillator circuit has been provided that allows for varying the center frequency of oscillation through an applied voltage signal (V.sub.F). Further, the center frequency of oscillation can be fine tuned around the center frequency via a modulation signal (S.sub.M). The voltage controlled oscillator circuit utilizes a negative resistance technique for oscillation and includes an output amplifier whose output resistance can be adjusted to match the input impedance of another circuit for maximum drive capability.
Claims9
A voltage controlled oscillator circuit having first, second and third terminals, an external inductor being coupled across the first and second terminals, a control voltage being applied to the third terminal, comprising:
- an oscillator circuit being coupled to the first and second terminals for providing an output signal having a predetermined center frequency, said oscillator circuit including a transistor having a predetermined negative input resistance such that said oscillator circuit sustains oscillation, said oscillator circuit being responsive to the control voltage such that when the control voltage is varied, said center frequency of said output signal of said oscillator circuit is varied;
- and
- an output amplifier having an input and an output, said input of said output amplifier being coupled to receive said output signal of said oscillator circuit, said output of said output amplifier being coupled to an output terminal of the voltage controlled oscillator circuit, said output amplifier having an adjustable output impedance.
A voltage controlled oscillator circuit having first, second and third terminals, an external inductor being coupled across the first and second terminals, a control voltage being applied to the third terminal, comprising:
- an oscillator circuit being coupled to the first and second terminals for providing an output signal having a predetermined center frequency, said oscillator circuit including a transistor having a predetermined negative input resistance such that said oscillator circuit sustains oscillation, said oscillator circuit being responsive to the control voltage such that when the control voltage is varied, said center frequency of said output signal of said oscillator circuit is varied;
- a modulation circuit for applying an ac voltage signal to said oscillator circuit such that the frequency of said output signal of said oscillator circuit is modulated around said predetermined center frequency;
- and
- an output amplifier having an input and an output, said input of said output amplifier being coupled to receive said output signal of said oscillator circuit, said output of said output amplifier being coupled to an output terminal of the voltage controlled oscillator circuit, said output amplifier having an adjustable output impedance.
Dependencies are inferred from the claim text.