VCO with automatic calibration
AssigneeSequoia Communications
InventorsJohn Groe, Joseph Austin
Life of this patent
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Abstract
Voltage-controlled oscillator with apparatus for automatic calibration. The voltage-controlled oscillator includes switches connecting associated coarse-tuning capacitors to an LC resonant tank of the oscillator. The voltage-controlled oscillator also comprises a calibration loop used to appropriately set the switches associated with the coarse tuning apparatus based on a oscillator control signal.
Claims26
Apparatus for automatic tuning of a voltage-controlled oscillator within a phase-locked loop, the apparatus comprising:
- a voltage-controlled oscillator that includes switches connecting associated coarse-tuning capacitors to an LC resonant tank of the oscillator;
- and
- a calibration loop used to appropriately set the switches associated with the coarse tuning capacitors, wherein the calibration loop comprises logic that operates to provide a selected settling time.
A method for automatic tuning of a voltage-controlled oscillator within a phase-locked loop, the method comprising steps of:
- operating a phase-locked loop that includes a voltage-controlled oscillator with coarse-tuning elements;
- setting switches in a way that successively disconnects the coarse-tuning elements to the voltage-controlled oscillator;
- waiting for a selected settling time;
- monitoring a phase-locked loop control voltage after each successive switch is opened;
- and
- indicating whether the control voltage is one of above, below, and within a prescribed operating range.
A method for automatic calibration of a VCO within a PLL, the method comprising steps of:
- operating the PLL and the VCO to produce a VCO control signal, wherein a plurality of coarse-tuning elements are coupled to a tank circuit of the VCO by a plurality of switches;
- setting selected switches so that coarse-tuning elements associated with the selected switches are coupled to the tank circuit;
- waiting for a selected settling time;
- comparing the VCO control signal to one or more reference signals to determine if the VCO control signal is within a desired range;
- and
- repeating the steps of setting and comparing until the VCO control signal is within the desired range.
Apparatus for automatic calibration of a VCO in a PLL, wherein the VCO comprises an LC resonant tank circuit, the apparatus comprising:
- a plurality of coarse-tuning capacitors;
- a plurality of switches operable to selectively connect the plurality of coarse-tuning capacitors to the LC resonant tank circuit based on a VCO control voltage;
- and
- logic to wait a selected settling time.
A communication device that comprises a PLL and associated VCO, wherein the VCO comprises an LC resonant tank circuit and the communication device further comprises apparatus for automatic calibration of the VCO, the apparatus comprising:
- a plurality of coarse-tuning capacitors;
- a plurality of switches operable to selectively connect the plurality of coarse-tuning capacitors to the LC resonant tank circuit based on a VCO control voltage;
- and
- logic to wait a selected settling time.
Apparatus for automatic tuning of a voltage-controlled oscillator, the apparatus comprising:
- course tuning means coupled to the voltage-controlled oscillator, the course tuning means operates to selectively connect coarse-tuning elements to an LC resonant tank of the voltage-controlled oscillator based on a switch signal;
- calibration loop means that operates to output the switch signal;
- and
- settling time means that operates to provide a selected settling time for the calibration loop means.
Dependencies are inferred from the claim text.