All-digital frequency synthesis with non-linear differential term for handling frequency perturbations
First Claim
1. An apparatus for controlling a digitally controlled oscillator device in a frequency synthesizer, comprising:
- an output for providing a digital control word that includes information for use in tuning the digitally controlled oscillator device;
a first input for receiving a first digital value produced in response to the frequency synthesizer and representative of a first phase difference, at a first point in time, between a reference signal and an output signal produced by the digitally controlled oscillator device;
a second input for receiving a second digital value produced in response to the frequency synthesizer and representative of a second phase difference, at a second point in time which is timewise separated from the first point in time, between the reference signal and said output signal; and
a gain controller coupled to said first and second inputs and said output for adjusting said digital control word based on said first and second digital values.
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Abstract
An all-digital frequency synthesizer architecture is built around a digitally controlled oscillator (DCO) that is tuned in response to a digital tuning word (OTW). In exemplary embodiments: (1) a gain characteristic (KDCO) of the digitally controlled oscillator can be determined by observing a digital control word before and after a known change (Δfmax) in the oscillating frequency; (2) a portion (TUNE_TF) of the tuning word can be dithered (1202), and the resultant dithered portion (dkTF) can then be applied to a control input of switchable devices within the digitally controlled oscillator; and (3) a non-linear differential term (187, 331) can be used to expedite correction of the digitally controlled oscillator when large phase error changes (335) occur.
79 Citations
36 Claims
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1. An apparatus for controlling a digitally controlled oscillator device in a frequency synthesizer, comprising:
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an output for providing a digital control word that includes information for use in tuning the digitally controlled oscillator device;
a first input for receiving a first digital value produced in response to the frequency synthesizer and representative of a first phase difference, at a first point in time, between a reference signal and an output signal produced by the digitally controlled oscillator device;
a second input for receiving a second digital value produced in response to the frequency synthesizer and representative of a second phase difference, at a second point in time which is timewise separated from the first point in time, between the reference signal and said output signal; and
a gain controller coupled to said first and second inputs and said output for adjusting said digital control word based on said first and second digital values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A data processing apparatus, comprising:
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a data processor for performing digital data processing operations;
a man/machine interface coupled to said data processor for permitting a user to communicate with said data processor;
a frequency synthesizer coupled to said data processor for producing a periodic signal having a desired frequency for use in transferring data produced by said data processor, said frequency synthesizer including a digitally controlled oscillator device; and
an apparatus coupled to said frequency synthesizer for controlling said digitally controlled oscillator device, including an output for providing a digital control word that includes information for use in tuning the digitally controlled oscillator device, a first input for receiving a first digital value produced in response to the frequency synthesizer and representative of a first phase difference, at a first point in time, between a reference signal and an output signal produced by the digitally controlled oscillator device, a second input for receiving a second digital value produced in response to the frequency synthesizer and representative of a second phase difference, at a second point in time which is timewise separated from the first point in time, between the reference signal and said output signal, and a gain controller coupled to said first and second inputs and said output for adjusting said digital control word based on said first and second digital values. - View Dependent Claims (19, 20, 21, 22)
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23. A method of controlling a digitally controlled oscillator device in a frequency synthesizer, comprising:
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receiving a first digital value produced in response to the frequency synthesizer and representative of a first phase difference, at a first point in time, between a reference signal and an output signal produced by the digitally controlled oscillator device;
receiving a second digital value produced in response to the frequency synthesizer and representative of a second phase difference, at a second point in time which is timewise separated from the first point in time, between the reference signal and said output signal; and
based on said first and second digital values, adjusting a digital control word that includes information for use in tuning the digitally controlled oscillator device. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. A data processing apparatus, comprising:
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a data processor for performing digital data processing operations;
a frequency synthesizer coupled to said data processor for producing a periodic signal having a desired frequency for use in transferring data produced by said data processor, said frequency synthesizer including a digitally controlled oscillator device; and
an apparatus coupled to said frequency synthesizer for controlling said digitally controlled oscillator device, including an output for providing a digital control word that includes information for use in tuning the digitally controlled oscillator device, a first input for receiving a first digital value produced in response to the frequency synthesizer and representative of a first phase difference, at a first point in time, between a reference signal and an output signal produced by the digitally controlled oscillator device, a second input for receiving a second digital value produced in response to the frequency synthesizer and representative of a second phase difference, at a second point in time which is timewise separated from the first point in time, between the reference signal and said output signal, and a gain controller coupled to said first and second inputs and said output for adjusting said digital control word based on said first and second digital values. - View Dependent Claims (35)
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36. A frequency synthesizer apparatus, comprising:
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a control loop for providing a digital control word;
a digitally controlled oscillator device coupled to said control loop for producing in response to said digital control word a periodic signal having a desired frequency; and
an apparatus coupled to said control loop for adjusting said digital control word, including a first input for receiving a first digital value produced in response to said control loop and representative of a first phase difference, at a first point in time, between a reference signal and an output signal produced by the digitally controlled oscillator, a second input for receiving a second digital value produced in response to said control loop and representative of a second phase difference, at a second point in time which is timewise separated from the first point in time, between the reference signal and said output signal, and a gain controller coupled to said first and second inputs for adjusting said digital control word based on said first and second digital values.
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Specification