Varactor folding technique for phase noise reduction in electronic oscillators
AssigneeBroadcom Corporation
InventorsRamon Alejandro Gomez, Lawrence M. Burns, Alexandre Kral
Life of this patent
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Abstract
A varactor folding technique reduces noise in controllable electronic oscillators through the use of a series of varactors having relatively small capacitance. A folding circuit provides control signals to the varactors in a sequential manner to provide a relatively smooth change in the total capacitance of the oscillator. Consequently, effective control of the oscillator is achieved with accompanying reductions in oscillator noise such as flicker noise.
Claims17
A controllable oscillator, responsive to at least one control signal, comprising:
- at least one folding circuit responsive to the at least one control signal, the at least one folding circuit generating a plurality of varactor control signals;
- and
- at least one oscillator circuit comprising a plurality of varactors responsive to the plurality of control signals wherein the varactors influence an operating frequency of the oscillator.
A controllable oscillator comprising:
- at least one oscillator circuit comprising a plurality of varactors;
- a plurality of capacitors;
- at least one switch for electrically coupling a plurality of varactor control signals to the varactors and for electrically isolating the varactors from the oscillator circuit;
- and
- at least one switch for electrically coupling the capacitors to the oscillator circuit.
A controllable oscillator, responsive to at least one control signal defining a plurality of voltage ranges, comprising:
- at least one oscillator circuit comprising a plurality of varactors responsive to a plurality of varactor control signals;
- a first transistor, responsive to a first one of the voltage ranges of the control signal, for generating a first one of the varactor control signals to control a first one of the varactors;
- and
- a second transistor, responsive to a second one of the voltage ranges of the control signal, for generating a second one of the varactor control signals to control a second one of the varactors.
A method of controlling an operating frequency of an oscillator that comprises a plurality of varactors, the method comprising the steps of:
- receiving at least one signal relating to a desired change in the operating frequency of the oscillator;
- providing a plurality of varactor control signals to a plurality of the varactors to alter capacitances of a plurality of the varactors to change the operating frequency of the oscillator.
A method of controlling an operating frequency of an oscillator that comprises a plurality of varactors, the method comprising the steps of:
- receiving at least one control signal relating to a desired change in the operating frequency of the oscillator;
- generating a first varactor control signal when a level of the control signal is equal to a first signal level;
- providing the first varactor control signal to a first one of the varactors to alter a capacitance of the first varactor to change the operating frequency of the oscillator;
- generating a second varactor control signal when a level of the control signal is equal to a second signal level;
- and
- providing the second varactor control signal to a second one of the varactors to alter a capacitance of the second varactor to effect a change in the operating frequency of the oscillator.
A method of controlling an operating frequency of an oscillator, the method comprising the steps of:
- electrically coupling a varactor control signal to the varactor;
- applying the varactor control signal to the varactor to alter a capacitance of the varactor to change the operating frequency of the oscillator
- electrically isolating the varactor from the oscillator;
- and
- electrically coupling a capacitor to the oscillator circuit.
Dependencies are inferred from the claim text.