VCO with phase modulated output
AssigneeNEC Corporation
InventorsHiromi Honma, Kinji Kayanuma
Life of this patent
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Abstract
A VCO, which good temperature characteristics, high frequency accuracy, and high phase accuracy is provided as an LSI, without making its master clock frequency operate the VCO high. The VCO includes a digital VCO, a phase modulator, and a frequency band limiting element. The digital VCO outputs an oscillating frequency clock and a phase difference lower than an output cycle resolution at the same timing as the output of the oscillating frequency clock. The phase modulator makes side-band components of the output from the digital VCO move from positions near the fundamental frequency to farther bands by modulating the phase of the output from the digital VCO based on the phase difference.
Claims14
A voltage controlled oscillator (VCO), comprising:
- a digital VCO that outputs an oscillating frequency clock based on a digital frequency control input signal;
- a phase modulator to which said oscillating frequency clock outputted from said digital VCO is inputted;
- and
- a frequency band limiting means to which an output from said phase modulator is inputted, wherein:
- said digital VCO also outputs a phase difference lower than an output cycle resolution decided by a master clock frequency to operate said digital VCO at the same timing of the output of said oscillating frequency clock,
- said phase modulator makes side-band components of the output from said digital VCO move from positions near a fundamental frequency to farther bands by modulating the phase of the output from said digital VCO based on said phase difference, and
- said frequency band limiting means eliminates said side-band components moved to said farther bands by a frequency band limitation.
Dependencies are inferred from the claim text.