Increased frequency resolution in a synthesizer
AssigneeMotorola, Inc.
InventorThomas J. Kundmann
Life of this patent
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Abstract
A direct digital frequency synthesizer increases the frequency resolution of the analog output signal by using fractionalization techniques. The best integer value I.sub.FR of a digital signal is determined and the next integer value I.sub.FR +1 of a digital signal is used to determine a weighted fractionalized value of the digital signal. The fractionalized value of the digital signal is used to synthesize the analog output signal having increased frequency resolution. In addition, IFR and IFR+1 are optimally distributed during the weighting process to ensure a minimum cumulative phase error.
Claims26
A frequency synthesizer having increased frequency resolution of an analog output signal, the analog output signal being synthesized in accordance with a digital control signal, the frequency synthesizer comprising:
- means for distributing a first digital input signal for a first fractional interval N and a second digital input signal for a second fractional interval D-N;
- and
- means, coupled to said means for distributing, for synthesizing the analog output signal.
A frequency synthesizer having increased frequency resolution of an analog output signal, the analog output signal being synthesized in accordance with a digital input signal, the frequency synthesizer comprising:
- means for generating a first integer value for a first fractional interval N and for generating a second integer value for a second fractional interval D-N based on the digital input signal and for generating a weighted average of said first integer value and said second integer value to produce a first non-integer value;
- and
- means, coupled to said means for generating the weighted average, for synthesizing the analog output signal.
A transmitter incorporating a direct digital frequency synthesizer which synthesizes an analog output signal, the transmitter comprising:
- means for generating a first integer value for a first fractional interval and for generating a second integer value for a second fractional interval based on a digital input signal corresponding to a frequency of the analog output signal and for generating a weighted average of said first integer value and said second integer value to produce a first non-integer value;
- means, coupled to said means for generating the weighted average, for synthesizing the analog output signal;
- and
- means, coupled to said means for synthesizing, for transmitting a radio frequency signal having a frequency related to said analog output signal.
A method of increasing the frequency resolution of an analog output signal in a frequency synthesizer, the analog output signal being synthesized in accordance with a digital control signal, the method comprising the steps of:
- providing a first digital input signal for a first fractional interval N and a second digital input signal for a second fractional interval D-N;
- and
- distributing said first digital input signal and said second digital input signal over D fractional intervals to produce the digital control signal.
A method of increasing the frequency resolution of an analog output signal in a frequency synthesizer, the analog output signal being synthesized in accordance with a digital input signal, the method comprising the steps of:
- generating a first integer value for a first fractional interval N and generating a second integer value for a second fractional interval D-N based on the digital input signal;
- generating a weighted average of said first integer value and said second integer value to produce a first non-integer value;
- providing a reference signal having a fixed frequency;
- and
- synthesizing, based on said step of generating the weighted average and said step of providing the reference signal, the analog output signal.
A method of synthesizing an analog output signal in a frequency synthesizer incorporated in a transmitter, the method comprising the steps of:
- generating a first integer value for a first fractional interval and a second integer value for a second fractional interval based on a digital input signal corresponding to a frequency of the analog output signal;
- generating a weighted average of said first integer value and said second integer value to produce a first non-integer value;
- providing a reference signal having a fixed frequency;
- synthesizing, based on said step of generating the weighted average and said step of providing the reference signal, the analog output signal;
- and
- transmitting a radio frequency signal having a frequency related to said synthesized analog output signal.
Dependencies are inferred from the claim text.