Phase/frequency detector with time-delayed inputs in a charge pump based phase locked loop and a method for enhancing the phase locked loop gain
US6147561A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 29, 1999 |
| Grant date | Nov 14, 2000 |
| Priority date | — |
| Expiry date | Jul 29, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/0891
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A phase locked loop (PLL) circuit with time-delayed phase/frequency detector (PFD) input signals and a method for generating high PFD gain in such a circuit is provided. One circuit embodiment includes a first divider, a phase/frequency detector having a plurality of input pairs, a plurality of input signal reference delay elements connected in a series between the first divider and the PFD, a charge pump, a loop filter, a voltage-controlled oscillator (VCO), a second divider, and a plurality of feedback signal delay elements connected in a series. The corresponding method embodiment includes steps for receiving digital input signals with reference frequency and period T in the first divider, dividing the reference frequency by a value R, providing a plurality of time-delayed PFD reference input signals in each period T, dividing the VCO frequency by a value M in the second divider, and providing a plurality of time-delayed PFD feedback input signals in each period T. The delayed reference signal and the delayed feedback signal at each PFD input pair have the same time delay. Another embodiment circuit has a first divider, a plurality of phase/frequency detectors (PFDs), a charge p…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.