Techniques for minimizing control voltage ripple due to charge pump leakage in phase locked loop circuits
US7932757B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 9, 2009 |
| Grant date | Apr 26, 2011 |
| Priority date | — |
| Expiry date | Mar 14, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/18
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Techniques for adaptively control of a loop filter sampling interval to mitigate the effects of charge pump leakage current in an apparatus including a phase lock loop circuit are provided. In one aspect, the apparatus includes a voltage controlled oscillator (VCO), a phase frequency detector (PFD) providing a phase comparison operation, a loop filter providing a control voltage to lock the VCO to a desired operating frequency, and a charge pump configured to provide an output signal to the loop filter in response to at least one of an UP pulse and a DOWN pulse. The apparatus further includes a sampling switch, coupled between an input of the loop filter, an output of the charge pump, and characterized by a sampling interval. A sampling switch controller is configured to adaptively control the width of the sampling interval in order to mitigate the effects of leakage current from the charge pump by closing the sampling switch in advance of the phase comparison operation and opening the sampling switch when the phase comparison operation is completed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.