Phase frequency synchronism circuit and optical receiver
US6600797B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 3, 2000 |
| Grant date | Jul 29, 2003 |
| Priority date | — |
| Expiry date | Mar 3, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/0891
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
In order to solve the problem that since a loop filter constant suitable for asynchronous state cannot be selected in the conventional phase frequency synchronism circuit, it takes a long time to synchronize the input data and the clock signal from the asynchronous state, the present invention is to propose a phase frequency synchronism circuit including a phase comparator for generating a voltage according to the phase difference of the clock signal to the input signal, a frequency comparator for deciding if the frequency of the clock signal is higher or lower than the transmission rate of the input signal and generating a binary signal, a synchronous identifying unit for deciding if the input signal and the clock signal are synchronized in their phases and frequencies, a first switch that receives the output from the phase comparator and is closed and opened when the synchronous identifying unit decides that they are synchronized and not synchronized, respectively, a second switch that receives the output from the frequency comparator and is opened and closed when the synchronous identifying unit decides that they are synchronized and not synchronized, respectively, a loop filter…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.