Direct frequency synthesizer for offset loop synthesizer
AssigneeAgilent Technologies, Inc.
InventorWing J. Mar
Life of this patent
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Abstract
A direct frequency synthesizer provides an output signal derived from a high frequency reference signal that is frequency divided and mixed to satisfy the coarse step synthesis requirements of an offset loop synthesizer. The absence of a VCO within the direct frequency synthesizer, provides the direct frequency synthesizer with lower phase noise than a typical PLL-based coarse step synthesizer. Though applicable to a variety of types of synthesizers and signal generators, the direct frequency synthesizer provides especially advantageous noise performance when used to generate an offset signal for an offset loop synthesizer of the first local oscillator of a spectrum analyzer, where the second local oscillator of the spectrum analyzer provides the reference signal for the direct frequency synthesizer.
Claims20
A direct frequency synthesizer, comprising:
- a first frequency division path dividing an applied reference signal by a first divisor to provide a first signal;
- a second frequency division path dividing the reference signal by a second divisor to provide a second signal and dividing the second signal by a third divisor to provide a third signal, the second frequency division path having a mixer receiving the second signal and the third signal;
- and
- an output mixer receiving the first signal and a product of the second signal and the third signal, and providing an output signal having a frequency relationship to the applied reference signal.
A direct frequency synthesizer, comprising:
- a first frequency division path dividing an applied reference signal by a first divisor to provide a first signal;
- a second frequency division path dividing the reference signal by a second divisor to provide a second signal and further dividing the second divided signal by a third divisor to provide a third signal, the second frequency division path having a mixer receiving the second signal and the third signal;
- an output mixer receiving the first signal and a product of the second signal and the third signal, providing a first output signal having a frequency relationship to the applied reference signal;
- and
- an offset loop synthesizer receiving the first output signal and providing a second output signal related in frequency to the first output signal and an interpolation signal within the offset loop synthesizer.
A direct frequency synthesis method, comprising:
- dividing an applied reference signal by a first divisor to provide a first signal;
- dividing the reference signal by a second divisor to provide a second signal;
- dividing the second signal by a third divisor to provide a third signal;
- mixing the second signal and the third signal;
- and
- mixing a designated product of the second signal and the third signal with the first signal to provide an output signal related in frequency to the applied reference signal.
Dependencies are inferred from the claim text.