Extendible-range voltage controlled oscillator
AssigneesAT&T Global Information Solutions Company, Hyundai Electronics America
InventorsMichael B. Anderson, Frank Gasparik
Life of this patent
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Abstract
A circuit design extending the range and linearizing the transfer characteristic of a fast voltage controlled oscillator (VCO). In addition, a multi-range VCO is described. Range extension is achieved by modifying the delay cell of a current controlled ring oscillator. The VCO transfer characteristic is linearized by piece-wise linear current control added to the delay cell. Additionally, a VCO capable of multi-range operation is provided. With the addition of multiple current sources which control booster inverter current, and by selectively enabling the additional current sources, a VCO with multiple frequency ranges can be achieved.
Claims12
An extended range voltage controlled oscillator, comprising:
- a plurality of delay cells with booster inverters;
- a current source which restricts current in at least one of the booster inverters;
- and
- a bias circuit for piece-wise linearly biasing the current source.
An improved phase-locked loop circuit, comprising:
- a phase detector;
- a charge pump operatively coupled to the phase detector;
- a filter operatively coupled to the charge pump;
- and
- an oscillator operatively coupled to the filter, wherein the oscillator comprises (i) a plurality of delay cells with booster inverters;
- (ii) a controllable current source which restricts current in at least one of the booster inverters;
- and iii) a bias circuit for piece-wise linearly biasing the controllable current source.
A method for extending an operating range of a phase-locked loop circuit comprising a plurality of delay cells, the method comprising the steps of:
- controlling current in a booster inverter of at least one of said delay cells;
- and
- piece-wise linear biasing the booster inverter.
In combination:
- a booster inverter;
- and
- means for maintaining a constant current in the booster inverter at relatively low frequencies, and linearly increasing current in the booster inverter at relatively high frequencies.
Dependencies are inferred from the claim text.