Method and apparatus for extending a VCO tuning range
AssigneeConexant Systems, Inc.
InventorsAndrew Zhang, Roy H. Fladager
Life of this patent
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Abstract
Method and apparatus for extending a VCO tuning range. A shunt inductance connected in parallel with a varactor reduces the effective capacitance of the varactor and increases the capacitance ratio. This increases the VCO tuning range without increasing the tuning sensitivity variation and the phase noise.
Claims18
A method of extending a tuning range of a voltage controlled oscillator about a given operating frequency without substantially increasing tuning sensitivity variation and phase noise, the oscillator having a tank circuit which includes a varactor circuit having a change of capacitance over a range of a control voltage, the method comprises reducing effective capacitance of the varactor circuit in the tank circuit while substantially maintaining the change of capacitance over the range of the control voltage.
Extending tuning range circuitry for a voltage controlled oscillator, the circuitry comprising a tank circuit including
- a) a varactor;
- and
- b) a shunt inductance coupled in parallel with the varactor such that a parallel combination of the varactor and the shunt inductance has a smaller effective capacitance and a larger capacitance ratio than the varactor alone, and such that tuning sensitivity variation and phase noise of the voltage controlled oscillator about a given operating frequency remain substantially the same as with the varactor alone.
A tank circuit of a voltage controlled oscillator, the circuit comprising a varactor and means for extending a tuning range of the voltage controlled oscillator about a given operating frequency without substantially increasing tuning sensitivity variation and without substantially increasing phase noise.
Extending tuning range circuitry for a voltage controlled oscillator, the circuitry comprising:
- a) a tank circuit;
- b) means for providing voltage dependent capacitance in the tank circuit;
- and
- c) means for providing parallel inductance across the voltage dependent capacitance providing means to form a parallel combination in the tank circuit having reduced effective capacitance and greater capacitance ratio than the voltage dependent capacitance providing means alone, and to extend a tuning range of the voltage controlled oscillator about a given operating frequency while substantially maintaining tuning sensitivity variation and phase noise.
Dependencies are inferred from the claim text.