Method and apparatus for adjusting a digital control word to tune synthesized high-frequency signals for wireless communications
US6574288B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | May 29, 1998 |
| Grant date | Jun 3, 2003 |
| Priority date | — |
| Expiry date | May 29, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03J2200/10
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for synthesizing high-frequency signals is disclosed that overcomes integration problem associated with prior implementations while meeting demanding phase noise and other impurity requirements. In one embodiment, a phase-locked loop (PLL) frequency synthesizer is disclosed having a voltage controlled oscillator (VCO) with a variable capacitance that includes a discretely variable capacitance in conjunction with a continuously variable capacitance. The discretely variable capacitance may provide coarse tuning adjustment of the variable capacitance, and the continuously variable capacitance may provide a fine tuning adjustment of the variable capacitance. In a further detail, discrete control circuitry is disclosed that provides a digital control signal to a discretely variable capacitance circuit to control its overall capacitance and that adjusts the digital control signal depending upon feedback from the output frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.