Frequency hold mechanism in a clock and data recovery device
US8094754B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 3, 2008 |
| Grant date | Jan 10, 2012 |
| Priority date | — |
| Expiry date | Aug 14, 2030 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/22
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A system and method are provided for holding the frequency of a non-synchronous communication signal in a clock and data recovery (CDR) device frequency synthesizer. The method initially acquires the phase of a non-synchronous first communication signal having a first frequency, and divides a first synthesized signal by a selected frequency ratio value, creating a frequency detection signal having a frequency equal to a reference signal frequency. In response to losing the first communication signal and subsequently receiving a second communication signal with a non-predetermined second frequency, the frequency ratio value is retrieved from memory based upon the assumption that the second frequency is the same, or close to the first frequency. Using a phase-frequency detector (PFD), the reference signal, and the frequency ratio value, a second synthesized signal is generated having an output frequency equal to first frequency. Using a rotational frequency detector (RFD), the second communication signal, and the second synthesized signal, a second synthesized signal is generated having an output frequency equal to second frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.