Systems and methods for correcting phase locked loop tracking error using feed-forward phase modulation
AssigneeAgilent Technologies, Inc.
InventorRichard K. Karlquist
Life of this patent
Estimating the term…
Abstract
Tracking error in phase locked loop (PLL) devices is addressed utilizing feed-forward phase modulation. Specifically, the phase difference of the reference signal and said oscillator signal of a PLL may be determined utilizing a phase detector. The output of the phase detector may be provided to a loop filter to provide feedback to the VCO of the PLL. Additionally, the filtered phase difference may be provided to a suitably calibrated phase modulator to add an amount of phase modulation to the oscillator signal that is approximately equal and opposite to said phase difference to generate a corrected phase output signal.
Claims22
A device that is operable to provide a corrected phase output signal, said device comprising:
- a first phase detector that generates a first phase signal;
- a phase locked loop (PLL) that generates an oscillator signal that is related to a tuning signal, wherein said PLL comprises (i) a second phase detector that generates a second phase signal that is indicative of a phase difference between said oscillator signal and (ii) an input signal and a filter that filters said second phase signal to generate said tuning signal;
- and
- a phase modulator that receives said oscillator signal and said first phase signal that is indicative of a phase difference between said oscillator signal and said input signal, wherein said phase modulator generates said corrected phase output signal by adding, to said oscillator signal, an amount of phase modulation that is approximately equal and opposite to said phase difference between said oscillator signal and said input signal.
A phase locked loop (PLL) device that is operable to provide a corrected phase output signal, said PLL device comprising:
- a voltage controlled oscillator (VCO) that produces an oscillator signal that is related to a tuning signal;
- a phase detector that generates a first phase signal from an input signal and said oscillator signal;
- a phase modulator that receives said oscillator signal and said first phase signal, wherein said phase modulator generates said corrected phase output signal by adding, to said oscillator signal, an amount of phase modulation that is approximately equal and opposite to a phase difference between said input signal and said oscillator signal;
- a nonlinear phase detector that generates a second phase signal;
- and
- a filter that filters said second phase signal to generate said tuning signal.
A method of providing a corrected phase output signal, comprising:
- operating a phase locked loop (PLL) to provide an oscillator signal;
- generating a first phase signal that is indicative of a phase difference between said oscillator signal and an input signal;
- utilizing said first phase signal to phase modulate said oscillator signal by adding, to said oscillator signal, an amount of phase modulation that is approximately equal and opposite to said phase difference to generate said corrected phase output signal;
- generating a second phase signal that is indicative of a phase difference between said oscillator signal and said input signal with a nonlinear phase detector;
- filtering said second phase signal;
- and
- providing said second phase signal as a tuning signal to generate said oscillator signal.
Dependencies are inferred from the claim text.