Granted Patent B2

US 7,202,752 · App. 11/126,553 · Granted Apr 10, 2007

Abstract

Claims (64)

1. A phase locked loop comprising:

a difference detection module operably coupled to determine

a difference signal based on at least one of a phase difference and a frequency difference between a reference oscillation and a feedback oscillation;

a loop filter module operably coupled to convert the difference signal into a control signal;

a ring oscillator having a plurality of buffer stages and a plurality to taps coupled to a corresponding plurality of outputs of the plurality of buffer stages, the ring oscillator operably coupled to convert the control signal into an output oscillation;

an output oscillation adjust module operably coupled to the ring oscillator for producing an effective output oscillation based on an oscillation control signal, wherein the output oscillation adjust module includes an output select block, operably coupled to the plurality of taps, for producing the effective output oscillation from a sequence of selected taps from the plurality of taps, and a tap adjust control generator, responsive to the oscillation control signal for generating a sequence of tap adjust control signals that command the output select block to select the sequence of selected taps from the plurality of taps; and

a divider module operably coupled to convert the effective output oscillation into the feedback oscillation;

wherein the effective output oscillation has a frequency F eo and the output oscillation has a frequency F o and wherein |F eo −F o |/F o <0.5;

wherein the divider module is responsive to the oscillation control signal to produce the feedback oscillation by dividing the frequency of the effective output oscillation F eo by a selected divisor.

2. The phase locked loop of claim 1 wherein the tap adjust control generator includes an integrator having an integrator output, responsive to the oscillation control signal and a modulo(x) module for producing the sequence of tap adjust control signals based on the integrator output, wherein the value of x is equal to the number of the plurality of taps.

3. The phase locked loop of claim 1 wherein the divider module includes a fractional divider.

4. The phase locked loop of claim 1 wherein the effective output oscillation has a frequency eo and the output oscillation has a frequency F o and wherein F eo >F o .

5. A phase locked loop comprising:

a difference detection module operably coupled to determine a difference signal) based on at least one of a phase difference and a frequency difference between a reference oscillation and a feedback oscillation;

a loop filter module operably coupled to convert the difference signal into a control signal;

a controlled oscillation module operably coupled to convert the control signal into an output oscillation;

an output oscillation adjust module operably coupled to the controlled oscillation module to produce an effective output oscillation based on an oscillation control signal; and

a divider module operably coupled to convert the effective output oscillation into the feedback oscillation;

wherein the effective output oscillation has a frequency F eo and the output oscillation has a frequency F o and wherein F eo >F o .

6. The phase locked loop of claim 5 wherein the controlled oscillation module includes a ring oscillator having a plurality of buffer stages and a plurality of taps coupled to a corresponding plurality of outputs of the plurality of buffer stages.

7. The phase locked loop of claim 6 wherein output oscillation adjust module includes an output select block, operably coupled to the plurality of taps, for producing the effective output oscillation from one of the plurality of taps.

8. The phase locked loop of claim 7 wherein the output oscillation adjust module includes a tap adjust control generator, responsive to the oscillation control signal for generating a sequence of tap adjust control signals that command the output select block to select a corresponding sequence of selected taps from the plurality of taps.

9. The phase locked loop of claim 8 wherein the tap adjust control generator includes an integrator having an integrator output, responsive to the oscillation control signal and the reference oscillation, and a modulo(x) module for producing the sequence of tap adjust control signals based on the integrator output.

10. The phase locked loop of claim 9 wherein the value of x is equal to the number of the plurality of taps.

11. The phase locked loop of claim 5 wherein the effective output oscillation has a frequency and the divider module is responsive to the oscillation control signal to produce the feedback oscillation by dividing the frequency of the effective output oscillation by a selected divisor.

12. The phase locked loop of claim 5 wherein the divider module includes a fractional divider.

13. The phase locked loop of claim 11 wherein the selected divisor is an integer.

14. The phase locked loop of claim 5 wherein the effective output oscillation has a frequency F eo and the output oscillation has a frequency F o and wherein |F eo −F o |/F o <0.5.

15. A method for producing an output oscillation, the method comprising the steps of:

generating a difference signal based on at least one of phase a difference and a frequency difference between a reference oscillation and a feedback oscillation;

filtering the difference signal to produce a control signal;

converting the control signal into an output oscillation using a controlled oscillation module;

adjusting the output oscillation to produce an effective output oscillation based on an oscillation control signal; and

dividing the effective output oscillation by a selected divisor to produce the feedback oscillation;

wherein the effective output oscillation has a frequency F eo and the output oscillation has a frequency F o and wherein F eo >F o .

16. The method of claim 15 wherein the controlled oscillation module includes a ring oscillator having a plurality of buffer stages and a plurality of taps coupled to a corresponding plurality of outputs of the plurality of buffer stages.

17. The method of claim 16 wherein the step of adjusting the output oscillation further comprises, producing the effective output oscillation from one of the plurality of taps.

18. The method of claim 17 wherein the step of adjusting the output oscillation further comprises, selecting a corresponding sequence of selected taps from the plurality of taps based on a sequence of tap adjust control signals.

19. The method of claim 18 wherein the step of adjusting the output oscillation further comprises, generating the sequence, of tap adjust control signal using an integrator having an integrator output, responsive to the oscillation control signal and the reference oscillation, and a modulo(x) module for producing the sequence of tap adjust control signals based on the integrator output.

20. The method of claim 19 wherein the value of x is equal to the number of the plurality of taps.

21. The phase locked loop of claim 18 wherein the divider module includes a fractional divider.

22. The phase locked loop of claim 15 wherein the selected divisor is an integer.

23. The phase locked loop of claim 15 wherein the effective output oscillation has a frequency F eo and the output oscillation has a frequency F o and wherein |F eo −F o |/F o <0.5.

24. A local oscillator for use in a radio receiver for demodulating a radio signal that carries a plurality of audio channels into an audio output signal corresponding to a selected one of the plurality of audio channels, the local oscillator comprising:

a reference oscillator for producing a reference oscillation;

a channel selector for generating an oscillation control signal that corresponds to the selected one of the plurality of audio channels;

a difference detection module operably coupled to determine a difference signal based on at least one of a phase difference and a frequency difference between the reference oscillation and a feedback oscillation;

a loop filter module operably coupled to convert the difference signal into a control signal;

a controlled oscillation module operably coupled to convert the control signal into an output oscillation;

an output oscillation adjust module operably coupled to the controlled oscillation module to produce an effective output oscillation based on an oscillation control signal; and

a divider module operably coupled to convert the effective output oscillation into the feedback oscillation;

wherein the effective output oscillation has a frequency and the divider module is responsive to the oscillation control signal to produce the feedback oscillation by dividing the frequency of the effective output oscillation by a selected divisor.

25. The local oscillator of claim 24 wherein the controlled oscillation module includes a ring oscillator having a plurality of buffer stages and a plurality of taps coupled to a corresponding plurality of outputs of the plurality of buffer stages.

26. The local oscillator of claim 25 wherein output oscillation adjust module includes an output select block, operably coupled to the plurality of taps, for producing the effective output oscillation from one of the plurality of taps.

27. The local oscillator of claim 26 wherein the output oscillation adjust module includes a tap adjust control generator, responsive to the oscillation control signal for generating a sequence off tap adjust control signals that command the output select block to select a corresponding sequence of selected taps from the plurality of taps.

28. The local oscillator of claim 27 wherein the tap adjust control generator include an integrator having an integrator output, responsive to the oscillation control signal and the reference oscillation, and a modulo(x) module for producing the sequence of tap adjust control signs based on the integrator output.

29. The local oscillator of claim 28 wherein the value of x is equal to the number of the plurality of taps.

30. The phase locked loop of rim 24 wherein the divider module includes a fractional divider.

31. The phase locked loop of claim 24 wherein the selected divisor is an integer.

32. The local oscillator of claim 24 wherein the effective output oscillation has a frequency F eo and the output oscillation has a frequency F o and wherein F eo >F o .

33. The local oscillator of claim 24 wherein the effective output oscillation has a frequency F eo and the output oscillation has a frequency F o and wherein |F eo −F o |/F o <0.5.

34. A controlled oscillator comprising:

a ring oscillator having a plurality of buffer stages and a plurality of tape coupled to a corresponding plurality of outputs of the plurality of buffer stages, the ring oscillator operably coupled to convert a control signal into an output oscillation;

an output oscillation adjust module operably coupled to the ring oscillator for producing an effective output oscillation based on an oscillation control signal, wherein the output oscillation adjust module includes an output select block, operably coupled to the plurality of taps, for producing the effective output oscillation from a sequence of selected taps from the plurality of taps, and a tap adjust control generator, responsive to the oscillation control signal for generating a sequence of tap adjust control signals that command the output select block to select the sequence of selected taps from the plurality of taps, wherein the tap adjust control generator includes an integrator having an integrator output, responsive to the oscillation control signal and a modulo(x) module for producing the sequence of tap adjust control signals based on the integrator output, wherein the value of x is equal to the number of the plurality of taps.

Assignments (11)