Charge pump circuit for a phase locked loop
US9438254B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | May 21, 2015 |
| Grant date | Sep 6, 2016 |
| Priority date | — |
| Expiry date | May 21, 2035 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/099
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A phase-locked-loop includes a phase-frequency-detector (PFD) comparing phases of an input signal and feedback signal, and generating therefrom control signals. An attenuation circuit in series with the PFD includes a filter between a voltage-controlled-oscillator (VCO) control node and ground. A buffer is coupled to the VCO control node. An impedance network is coupled to the VCO control node and has an impedance element coupled to a first current source so voltage at the VCO control node increases when control signals indicate the phase of the input signal leads the feedback signal, and coupled to a second current source so voltage at the VCO control node decreases when control signals indicate a lagging phase. A VCO is coupled to the VCO control node to generate an output signal, with the phase of the output signal matching the input signal. The feedback signal is based upon the output signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.