Methods and apparatus for loop bandwidth control for a phase-locked loop
AssigneeTellabs Reston, Inc.
InventorsSharath Navil, David W. Fleming
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Abstract
A method for controlling loop bandwidth of a phase locked loop is described. The method includes setting the loop bandwidth to a value, calculating at least one of a phase error and a frequency change that occur subsequent to any setting or adjusting of loop bandwidth, and adjusting the loop bandwidth based on at least one of the phase error and the frequency change.
Claims31
A method for controlling loop bandwidth of a phase locked loop comprising:
- setting the loop bandwidth to a value;
- calculating a filtered phase error that occurs subsequent to any setting or adjusting of loop bandwidth;
- and
- adjusting the loop bandwidth based on the filtered phase error, wherein calculating the phase error comprises calculating an average phase error according to:
- Fphase error(i+1)=(Dphase error(F(i))+Gphase error×(Xphase error(i+1))+R(i))/(Dphase error+1), where, i is an integer, F(i) is a filter output from reading (i), Xphase error(i) is the phase error at reading (i), R(i) is a remainder output from the filter from reading (i), Dphase error is a damping factor, and Gphase error is a gain factor.
A method for controlling loop bandwidth of a phase locked loop comprising:
- setting the loop bandwidth to a value;
- calculating at least one of a phase error and a frequency change that occur subsequent to any setting or adjusting of loop bandwidth;
- and
- adjusting the loop bandwidth based on at least one of the phase error and the frequency change, wherein calculating at least one of a phase error and a frequency change comprises reading a stored frequency change and phase error, the stored frequency change being an average frequency change of an oscillator of the phase-locked loop over a term and the phase error being an average phase error of an oscillator of the phase-locked loop over a term.
A method for controlling loop bandwidth of a phase locked loop comprising:
- setting the loop bandwidth to a value;
- calculating a filtered frequency change that occur subsequent to any setting or adjusting of loop bandwidth;
- and
- adjusting the loop bandwidth based on the filtered frequency change, wherein calculating the frequency change comprises calculating an average frequency change according to:
- Ffrequency change(i+1)=(Dfrequency change×(F(i))+Gfrequency change×(Xfrequency change(i+1))+R(i))/(Dfrequency change+1), where, i is an integer, F(i) is an integer filter result from reading (i), Xfrequency change(i) is an integral frequency change at reading (i), R(i) is a remainder filter result from reading (i), Dfrequency change is a damping factor, Gfrequency change is a gain factor.
A phase-locked loop comprising:
- an oscillator outputting a frequency;
- a counter module receiving the frequency from said oscillator;
- a phase detector receiving a signal from said counter and a reference frequency;
- and
- a filter receiving an output of said phase detector, said filter operable to set a loop bandwidth, calculate a phase error that occur subsequent to any setting or adjusting of loop bandwidth, and adjust the loop bandwidth based on the phase error, wherein said filter calculates the phase error according to:
- Fphase error(i+1)=(D×(F(i))+G×(Xphase error(i+1))+R(i))/(D+1), where, i is an integer. F(i) is a filter output from reading (i);
- Xphase error(i) is the phase error at reading (i);
- R(i) is a remainder output from the filter from reading (i);
- Dphase error is a damping factor, and Gphase error is a gain factor.
Dependencies are inferred from the claim text.