Dither-less multi-stage noise shaping fractional-N frequency synthesizer systems and methods
US9225349B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 9, 2014 |
| Grant date | Dec 29, 2015 |
| Priority date | — |
| Expiry date | Jul 9, 2034 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/361
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A fractional-N divider of a frequency synthesizer is driven by a dither-less and seed-less multi-stage noise shaping (MASH) modulator to alleviate fractional spurious tones introduced by the cyclic train of division ratios from delta-sigma modulators. The MASH modulator includes at least two cascaded dither-less delta-sigma modulators where each modulator includes a first feedback loop the generates the modulator feedback signal, a second feedback loop that disrupts fractional spurious tones and a third feedback loop that provides approximately zero static error. The MASH modulator further includes a combining circuit delays at least one code sequence from at least one of the delta-sigma modulators and that combines the code sequence generated by each of the delta-sigma modulators and at least one delayed code sequence.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.