ADJUSTING TUNING SEGMENTS IN A DIGITALLY-CONTROLLED OSCILLATOR

• US 20140347137A1
• Filed: 05/23/2013
• Published: 11/27/2014
• Est. Priority Date: 05/23/2013
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel IP Corporation (Intel Corporation)
• Inventors: REY, Claudio, HARNISHFEGER, David, NGUYEN, Darin
• Granted Patent: US 9,490,825 B2
• Time in Patent Office: Days
• US Class Current: 331/16
• CPC Class Codes: H03B 5/124 the means comprising a voltage dependent capacitance
• CPC Class Codes: H03L 2207/06 Phase locked loops with a controlled oscillator having at least two frequency control terminals
• CPC Class Codes: H03L 7/099 concerning mainly the controlled oscillator of the loop
• CPC Class Codes: H03L 7/103 the additional signal being a digital signal
• CPC Class Codes: H03L 7/18 using a frequency divider or counter in the loop H03L7/20, H03L7/22 take precedence

Abstract

A circuit may include a digitally-controlled oscillator including a coarse frequency-tuning array with a multiple selectable coarse frequency-tuning segments. Each of the coarse frequency-tuning segments may have a coarse segment frequency step size. The digitally-controlled oscillator may also include a fine frequency-tuning array with multiple selectable fine frequency-tuning segments. The fine frequency-tuning array may have a fine array frequency step size that is at least twice the coarse segment frequency step size. The digitally-controlled oscillator may be configured to generate an output signal with a frequency based on the coarse frequency-tuning array and the fine frequency-tuning array.

Claims

1. A circuit comprising:

a digitally-controlled oscillator including;

a coarse frequency-tuning array with a plurality of selectable coarse frequency-tuning segments, each of the coarse frequency-tuning segments having a coarse segment frequency step size; and

a fine frequency-tuning array with a plurality of selectable fine frequency-tuning segments, the fine frequency-tuning array having a fine array frequency step size that is at least twice the coarse segment frequency step size; and

the digitally-controlled oscillator configured to generate an output signal with a frequency based on the coarse frequency-tuning array and the fine frequency-tuning array.

2. The circuit of claim 1, further comprising a controller configured to provide a first coarse-tuning code to the digitally-controlled oscillator:

wherein the digitally-controlled oscillator is configured to select a first coarse frequency-tuning segment of the plurality of coarse frequency-tuning segments based on the first coarse-tuning code and to generate the output signal at a first frequency based on the selected first coarse frequency-tuning segment,

the controller further configured to provide a second coarse-tuning code to the digitally-controlled oscillator, and

while the digitally-controlled oscillator continues to generate the output signal at the frequency, the digitally-controlled oscillator is configured to select a second coarse frequency-tuning segment of the plurality of coarse frequency-tuning segments based on the second coarse-tuning code.

3. The circuit of claim 2, wherein the controller is further configured to provide a first fine-tuning code to the digitally-controlled oscillator, wherein:

the digitally-controlled oscillator is further configured to select a first fine frequency-tuning segment of the plurality of fine frequency-tuning segments based on the first fine-tuning code and to generate the output signal at the first frequency based on the selected first coarse frequency-tuning segment and the selected first fine frequency-tuning segment,

the controller is further configured to provide a second fine-tuning code to the digitally-controlled oscillator, and

while the digitally-controlled oscillator continues to generate the output signal at the first frequency, the digitally-controlled oscillator is further configured to select a second fine frequency-tuning segment of the plurality of fine frequency-tuning segments based on the second fine-tuning code.

4. The circuit of claim 2, further comprising a loop filter configured to provide a first fine-tuning code to the digitally-controlled oscillator, wherein:

the digitally-controlled oscillator is further configured to select a first fine frequency-tuning segment of the plurality of fine frequency-tuning segments based on the first fine-tuning code and to generate the output signal at the first frequency based on the selected first coarse frequency-tuning segment and the selected first fine frequency-tuning segment,

the controller is further configured to provide a second fine-tuning code to the digitally-controlled oscillator, and

while the digitally-controlled oscillator continues to generate the output signal at the first frequency, the digitally-controlled oscillator is further configured to select a second fine frequency-tuning segment of the plurality of fine frequency-tuning segments based on the second fine-tuning code.

5. The circuit of claim 4, further comprising a digital phase-locked loop that includes the loop filter and the digitally-controlled oscillator.

6. The circuit of claim 4, wherein the controller is configured to provide the first fine-tuning code to the loop filter.

7. The circuit of claim 1, wherein the digitally-controlled oscillator is configured to generate an output signal at a first frequency based on either:

a selected first coarse frequency-tuning segment of the plurality of coarse frequency-tuning segments and a selected first fine frequency-tuning segment of the plurality of fine frequency-tuning segments;

or

a selected second coarse frequency-tuning segment of the plurality of coarse frequency-tuning segments and a selected second fine frequency-tuning segment of the plurality of fine frequency-tuning segments.

8. A method of adjusting tuning segments in a digitally-controlled oscillator, the method comprising:

determining a first coarse-tuning code and a first fine-tuning code used by a digitally-controlled oscillator to generate an output signal at a frequency;

determining a second coarse-tuning code and a second fine-tuning code used by the digitally-controlled oscillator to generate the output signal at the frequency;

applying the first coarse-tuning code and the first fine-tuning code to the digitally-controlled oscillator to generate the output signal at the frequency; and

while the digitally-controlled oscillator continues to generate the output signal at the frequency, transitioning to apply the second coarse-tuning code and the second fine-tuning code to the digitally-controlled oscillator.

9. The method of claim 8, further comprising determining an exchange rate between the first fine-tuning code and the second fine-tuning code.

10. The method of claim 9, wherein the transitioning to apply the second fine-tuning code includes applying the exchange rate to the first fine-tuning code to obtain the second fine-tuning code.

11. The method of claim 8, further comprising determining a first and a second crude-tuning code used by a digitally-controlled oscillator to generate the output signal at the frequency.

12. The method of claim 11, further comprising applying the first crude-tuning code to the digitally-controlled oscillator to generate the output signal at the frequency.

13. The method of claim 12, further comprising while the digitally-controlled oscillator continues to generate the output signal at the frequency, transitioning to apply the second crude-tuning code, the second coarse-tuning code, and the second fine-tuning code to the digitally-controlled oscillator.

14. The method of claim 13, further comprising determining a fine exchange rate between the first fine-tuning code and the second fine-tuning code and a coarse exchange rate between the first coarse-tuning code and the second coarse-tuning code.

15. The method of claim 14, wherein the transitioning to apply the second fine-tuning code includes applying the fine exchange rate to the first fine-tuning code to obtain the second fine-tuning code and the transitioning to apply the second coarse-tuning code includes applying the coarse exchange rate to the first coarse-tuning code to obtain the second coarse-tuning code.

16. A method of adjusting tuning segments in a digitally-controlled oscillator, the method comprising:

selecting a first coarse frequency-tuning state from a plurality of selectable coarse frequency-tuning states within a digitally-controlled oscillator;

selecting a first fine frequency-tuning state from a plurality of selectable fine frequency-tuning states within the digitally-controlled oscillator;

generating an output signal at a frequency based on the first coarse frequency-tuning state and the first fine frequency-tuning state using the digitally-controlled oscillator;

selecting a second coarse frequency-tuning state from the plurality of selectable coarse frequency-tuning states;

selecting a second fine frequency-tuning state from the plurality of selectable fine frequency-tuning states; and

generating the output signal at the frequency based on the second coarse frequency-tuning state and the second fine frequency-tuning state using the digitally-controlled oscillator without recalibrating the digitally-controlled oscillator.

17. The method of claim 16, wherein the second coarse frequency-tuning state is adjacent to the first coarse frequency-tuning state within the plurality of selectable coarse frequency-tuning states.

18. The method of claim 16, wherein the selecting the second fine frequency-tuning state is based on the first fine frequency-tuning state and an exchange rate, the exchange rate calculated based on the frequency of the output signal.

19. The method of claim 18, wherein when a first frequency range of the first coarse frequency-tuning state is higher than a second frequency range of the second coarse frequency-tuning state, the selecting the second fine frequency-tuning state is based on subtracting the exchange rate from the first fine frequency-tuning state.

20. The method of claim 18, wherein when a first frequency range of the first coarse frequency-tuning state is lower than a second frequency range of the second coarse frequency-tuning state, the selecting the second fine frequency-tuning state is based on adding the exchange rate to the first fine frequency-tuning state.