Direct digital synthesizer/direct analog synthesizer hybrid frequency synthesizer
First Claim
1. A frequency synthesizer comprising:
- digital frequency synthesis means for generating a digital frequency signal, converting said digital frequency signal to analog form, and providing an output of said converted digital frequency signal as a digital frequency synthesis means output signal wherein said digital frequency synthesis means output signal is of a predetermined frequency within a frequency range of f to f+Δ
f;
input stage analog frequency synthesis means for, receiving said digital frequency synthesis means output signal, receiving an input of a plurality of I input stage input signals wherein each input stage input signal of said plurality of I input stage input signals is in analog form and separated in frequency from a next one by a maximum frequency increment of Δ
f with a first one and a last one of said plurality of I input stage input signals are respectively of a frequency of fA and fA +(I-1)Δ
f, mixing a selected one of said plurality of I input stage input signals with said digital frequency synthesis means output signal and providing a resultant input stage output signal of a frequency within a frequency range of a minimum of fA +f to a maximum of fA +f+IΔ
f; and
output stage analog frequency synthesis means for, receiving said input stage output signal, receiving an input of a plurality of K output stage input signals wherein each output stage input signal of said plurality of K output stage input signals is in analog form and separated in frequency from a next one by a maximum frequency increment of IΔ
f with a first one and a last one of said plurality of K output stage input signals are respectively of a minimum and a maximum frequency of fN and fN +(K-1)IΔ
f, mixing a selected one of said plurality of K output stage input signals with said input stage output signal and providing a resultant output stage output signal of a frequency within a frequency range of a minimum of fN +fA +f to a maximum of fN +fA +f+KIΔ
f.
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Abstract
A digital/analog hybrid frequency synthesizer having a digital frequency synthesizer for digitally generating an analog output signal of a predetermined frequency within a frequency range of f to f+Δf; an input stage analog frequency synthesizer for, receiving the digital frequency synthesizer output signal and I analog input stage input signals, each input stage input signal separated in frequency from a next one by a frequency increment of Δf wherein a first one and a last one of the input stage input signals are respectively of a frequency of fA and fA +(I-1)Δf, selecting one input stage input signal from the input stage input signals, mixing the selected input stage input signal with the digital frequency synthesizer output signal and providing a resultant input stage output signal; and an output stage analog frequency synthesizer for, receiving the input stage output signal and K analog output stage input signals, each output stage input signal separated in frequency from a next one by a frequency increment of IΔf wherein a first one and a last one of the output stage input signals are respectively of a frequency of fN and fN +(K-1)IΔf, selecting one output stage input signal from the output stage input signals, mixing the selected output stage input signal with the input stage output signal and providing a resultant output stage output signal. Additional intermediate frequency stages may be employed to facilitate greater bandwidth expansion.
49 Citations
32 Claims
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1. A frequency synthesizer comprising:
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digital frequency synthesis means for generating a digital frequency signal, converting said digital frequency signal to analog form, and providing an output of said converted digital frequency signal as a digital frequency synthesis means output signal wherein said digital frequency synthesis means output signal is of a predetermined frequency within a frequency range of f to f+Δ
f;input stage analog frequency synthesis means for, receiving said digital frequency synthesis means output signal, receiving an input of a plurality of I input stage input signals wherein each input stage input signal of said plurality of I input stage input signals is in analog form and separated in frequency from a next one by a maximum frequency increment of Δ
f with a first one and a last one of said plurality of I input stage input signals are respectively of a frequency of fA and fA +(I-1)Δ
f, mixing a selected one of said plurality of I input stage input signals with said digital frequency synthesis means output signal and providing a resultant input stage output signal of a frequency within a frequency range of a minimum of fA +f to a maximum of fA +f+IΔ
f; andoutput stage analog frequency synthesis means for, receiving said input stage output signal, receiving an input of a plurality of K output stage input signals wherein each output stage input signal of said plurality of K output stage input signals is in analog form and separated in frequency from a next one by a maximum frequency increment of IΔ
f with a first one and a last one of said plurality of K output stage input signals are respectively of a minimum and a maximum frequency of fN and fN +(K-1)IΔ
f, mixing a selected one of said plurality of K output stage input signals with said input stage output signal and providing a resultant output stage output signal of a frequency within a frequency range of a minimum of fN +fA +f to a maximum of fN +fA +f+KIΔ
f. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A high resolution, expanded bandwidth frequency synthesizer comprising:
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a digital frequency synthesizer capable of digitally generating an analog output signal in a frequency range of fmin to fmin +Δ
f comprising;a direct digital synthesizer (DDS) having a phase data input, a DDS clock input, and a DDS output; a digital to analog converter (DAC) having a data input coupled to said DDS output, a clock input and an output; a filter having an input coupled to said DAC output and an output; an analog input frequency synthesizer capable of converting said digital frequency output signal to an input frequency synthesizer signal in a frequency range of (fA +fmin) to (fA +fmin +IΔ
f) comprising;a first mixer having a pair of inputs and an output, one of said first mixer inputs coupled to said digital frequency synthesizer filter output and another one of said first mixer inputs for receiving a selected input signal of a first plurality of I input signals each different from one another by a frequency increment Δ
f, a first input signal of said first plurality of input signals at a frequency of fA and a last input signal of said first plurality of input signals at a frequency of fA +(I-1)Δ
f;a plurality of bandpass filters each having an input and an output, said bandpass filter outputs electrically coupled together; and filter selector means, coupled to said first mixer output, for receiving a first selector signal and responsive thereto for coupling said first mixer output to an input of a selected one of said bandpass filters; and an analog output frequency synthesizer capable of converting said input frequency synthesizer signal to an output frequency synthesizer signal in a frequency range of (fA +fB +fmin) to (fA +fB +fmin +KIΔ
f) comprising;a second mixer having a pair of inputs and an output, one of said second mixer inputs electrically coupled to said bandpass filter outputs and another one of said second mixer inputs for receiving a selected input signal of a a second plurality of K input signals each different from one another by a frequency increment IΔ
f, a first input signal of said second plurality of input signals at a frequency of fN and a last input signal of said second plurality of input signals at a frequency of fN +(K-1)IΔ
f; andan output bandpass filter having an input and an output, said output bandpass filter input coupled to said second mixer output. - View Dependent Claims (17, 18, 19, 20, 21)
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22. A method for frequency synthesis comprising the steps of:
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generating through direct digital synthesis and digital to analog signal conversion a first output signal of a predetermined frequency within a frequency range of f to f+Δ
f;mixing a first input signal of a first plurality of I input signals with said first output signal and providing a resultant second output signal, each input signal of said first plurality of input signals separated in frequency from a next one by a frequency increment of Δ
f and wherein first and last input signals of said first plurality of input signals are respectively of a frequency of fA and fA +(I-1)Δ
f; andmixing a second input signal of a second plurality of K input signals with said second output signal and providing a resultant third output signal, each input signal of said second plurality of input signals separated in frequency from a next one by a frequency increment of IΔ
f wherein first and last input signals of said second plurality of input signals are respectively of a frequency of fN and fN +(K-1)IΔ
f, and wherein said third output signal is of a frequency in the frequency range of fN +fA +f to fN +fA +f+KIΔ
f. - View Dependent Claims (23, 24)
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25. An apparatus for providing expanded bandwidth, high resolution frequency synthesis, comprising:
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first frequency synthesis means for generating a digital frequency signal representative of an analog frequency signal of a predetermined frequency within a frequency range of f to f+Δ
f, converting said digital signal to analog form, and providing said converted digital frequency signal as a first output signal; andsecond frequency synthesis means for, combining said first output signal with a selected one of a first plurality of I analog input signals each separated in frequency from a next one another by a maximum frequency increment of Δ
f with a first and last one respectively of a minimum and maximum frequency of fA and fA +(I-1)Δ
f, and providing a resultant analog second output signal in the frequency range of fA +f to fA +f+IΔ
f. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32)
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Specification