Multiple bandwidth phase lock filters for multimode radios
US6819197B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jan 29, 2002 |
| Grant date | Nov 16, 2004 |
| Priority date | — |
| Expiry date | Mar 31, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/18
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An apparatus and method for filtering a signal in a phase lock loop is disclosed. An typical apparatus for filtering a phase error signal comprises a first filter subcircuit receiving a phase error signal from a phase comparator and filtering the error signal when enabled, a second filter subcircuit receiving the phase error signal from the phase comparator and filtering the error signal when enabled and first and second enable switches which are activated in combination to control filtering of at the error signal. The first filter subcircuit is enabled by activating a first combination of the enable switches and the second filter subcircuit is enabled by activating a second combination of the enable switches. A fast acquisition subcircuit can also be used to temporarily underdampen the filter and improve overall performance of the phase lock loop circuit. The filter can be used to obtain multimode operation in a cellular radio.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.