High speed phase frequency detector
US7940088B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 31, 2009 |
| Grant date | May 10, 2011 |
| Priority date | — |
| Expiry date | Jun 9, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03D13/004
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Apparatus and methods detect missing clock edges. An improved phase frequency detector (PFD) can be used in, for example, a phase locked loop (PLL) or a delay locked loop (DLL). Conventional PFDs can miss clock edges. Disclosed is a missing clock edge detection circuit that reliably detects these missing clock edges to correctly activate switches of a charge pump of the PLL or DLL. Embodiments exhibit relatively little of the characteristic polarity reversal of conventional PLL or DLL circuits, which then enables embodiments to operate faster and acquire phase lock quicker than conventional circuits. Such techniques are useful in clock synthesis, clock recovery, and the like. The invention can further include an optional circuit that detects when the missing clock edge detection circuit may have inaccurately determined (false positive) that a clock edge had been missed, to override the corrective action by the missing clock edge detection circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.