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.
Claims6
A Controllable oscillator comprising:
- at least one oscillator circuit comprising a plurality of varactors;
- a plurality of capacitors;
- at least one such 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 of claim wherein at least one switch for electrically coupling and electrically isolating isolates a varactor by establishing a high impedance between the varactor and an alternating current ground.
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.