Circuit and method of extending the linear range of a phase frequency detector
US6100721A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 1, 1999 |
| Grant date | Aug 8, 2000 |
| Priority date | — |
| Expiry date | Feb 1, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0067
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A wireless communication system (10) uses a phase detector (28) having a first pair of flip-flops (50, 56) for detecting the phase difference between an input frequency and a reference frequency. The first pair of flip-flops control current sources (66, 70) in the charge pump of the phase detector to modulate the error signal. A second pair of flip-flops (52, 58) detect when the input frequency is more than 2.pi. ahead of or behind the reference frequency. The second pair of flip-flops increment and decrement a counter (54) which in turn controls additional current sources (78-88) in the charge pump. The additional current sources extend the linear operating range of the error signal when the phase error exceeds .+-.2.pi..
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.