All-digital frequency synthesis with non-linear differential term for handling frequency perturbations

A data processing apparatus, comprising:

• 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.

A method of controlling a digitally controlled oscillator device in a frequency synthesizer, comprising:

• 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.

A data processing apparatus, comprising:

• 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.

A frequency synthesizer apparatus, comprising:

• 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.