Method for extending the output range of pulse-width based phase detectors
US5952853A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 23, 1997 |
| Grant date | Sep 14, 1999 |
| Priority date | — |
| Expiry date | Dec 23, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/089
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A circuit for generating a signal that is proportional to the phase difference between a reference signal and a variable frequency signal. The circuit includes a reference generating circuit for generating N phase shifted reference signals from the reference signal. Each of the phase shifted reference signals has the same frequency and a different phase. The phase of the n.sup.th one of the phase shifted reference signals is equal to 360n/N degrees, where N>1 and n runs from 0 to N-1. A phase detection circuit generates a phase output signal proportional to the phase difference between the variable frequency signal and the phase shifted reference signal currently being outputted by the reference generating circuit. The phase output signal has value of I when the output signal corresponds to a phase difference of 360/N degrees. An overflow detection circuit determines when the phase output signal has an absolute value greater than I and generates a count signal and a phase adjustment signal when this situation is detected. The phase adjustment signal is coupled to the reference generating circuit and causes the reference generating circuit to select a new phase shifted reference sig…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.