Sample and hold type fractional-N frequency synthesizer
US6704383B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 29, 2001 |
| Grant date | Mar 9, 2004 |
| Priority date | — |
| Expiry date | Aug 29, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/095
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A phase-locked loop (PLL) fractional-N type frequency synthesizer incorporates a sample-and-hold circuit. The synthesizer can reduce circuit size by eliminating a loop filter. Further, the synthesizer can incorporate fractional spur compensation circuitry to compensate charge pump ripple whenever a charge pump operates. The synthesizer or fractional-N type PLL can use a divider and at least two phase detectors coupled to a sample-and-hold circuit. A lock detecting circuit can initially determine a reference voltage for the sample-and-hold circuit. Also, fractional compensation is accomplished dynamically and in a manner that is robust to environmental changes while a control voltage is stably maintained for the voltage controlled oscillator.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.