US 2013/0093483 A1 · Dual Phase Detector Phase-Locked Loop

Abstract

A phase-locked loop for generating an output signal that has a predetermined frequency relationship with a reference signal, the phase-locked loop comprising a signal generator arranged to generate the output signal, a charge pump arranged to generate current pulses for controlling the signal generator, two control units for controlling a duration of the current pulses generated by the charge pump and a selection unit arranged to select either the first control unit or the second control unit to control the charge pump, wherein a first one of the control units is arranged to continuously monitor a phase-difference between the reference signal and a feedback signal formed from the output signal and to, when selected by the selection unit, control the charge pump to output a current pulse having a duration that is dependent on that phase-difference and a second one of the control units is arranged to, when selected by the selection unit, control the charge pump to output a current pulse of predetermined duration that compensates for a phase error in the feedback signal.

Claims6

Dependent claims

A phase-locked loop for generating an output signal that has a predetermined frequency relationship with a reference signal, the phase-locked loop comprising a signal generator arranged to generate the output signal, a divider arranged to receive the output signal and divide the output signal to form a feedback signal, the divider being arranged to vary the divisor by which the output signal is divided, a comparison unit arranged to compare the feedback signal with the reference signal and a charge pump arranged to generate current pulses for controlling the signal generator in dependence on said comparison, the phase-locked loop being arranged such that:

when the comparison unit determines that the phase-locked loop is in a locked condition, the charge pump generates current pulses in dependence on an error in the feedback signal that is caused by the variation of the divisor;
and
when the comparison unit determines that the phase-locked loop is not in the locked condition, the charge pump does not generate current pulses in dependence on an error in the feedback signal that is caused by the variation of the divisor.

Dependencies are inferred from the claim text.

Dual Phase Detector Phase-Locked Loop

Life of this patent

Dual Phase Detector Phase-Locked Loop

Life of this patent

Abstract

Claims6