Fractional-N frequency synthesizer and method of operating the same
US6670854B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 10, 2002 |
| Grant date | Dec 30, 2003 |
| Priority date | — |
| Expiry date | Jul 10, 2022 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S331/02
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A fractional-N frequency synthesizer is offered which does not produce spurious signals of periodically conspicuous spectral intensities and can cancel produced spurious signals up to a practical level even with a spurious-canceling circuit of low accuracy. The synthesizer has a sigma-delta noise shaper. The integral and fractional parts of a frequency divide ratio-setting value that frequency-divides the output signal are set. The fractional part of the frequency divide ratio-setting value is applied to the sigma-delta noise shaper every phase comparison period. The output from the noise shaper and the integral part of the frequency divide ratio-setting value are summed up to thereby produce a sum. The output signal is frequency-divided, using this sum as a frequency divide ratio. The difference between the fractional part of the frequency divide ratio-setting value and the output from the sigma-delta noise shaper is produced and accumulated in an accumulator every phase comparison period. The spurious-canceling value is produced based on the value of the accumulator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.