Switch-capacitor loop filter for phase lock loops
US7629854B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 17, 2006 |
| Grant date | Dec 8, 2009 |
| Priority date | — |
| Expiry date | Jan 13, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/1976
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A switch-capacitor loop filter is used to generate a control voltage for a voltage-controlled oscillator (VCO) in a phase lock loop (PLL). The switch-capacitor circuit works in a multi-phase manner including at least two non-overlapping phases: a sampling phase and a transfer phase. During the sampling phase, the current representing the phase difference between the reference clock and the feedback clock of the PLL is integrated by a sampling capacitor. During the transfer phase, the charge stored on the sampling capacitor is transferred to a load capacitor. The timing for controlling the switch-capacitor function is derived from the reference clock.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.