Patent application number | Description | Published |
20100321075 | Dual Phase Detector Phase-Locked Loop - 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. | 12-23-2010 |
20110012652 | Phase-Locked Loop - A loop filter for receiving an input signal indicative of a phase-difference between a reference signal and a signal output by a signal generator and forming a control signal for controlling the signal generator in dependence thereon, the loop filter comprising a plurality of filter components that determine the frequency response of the filter, said filter components being arranged so that a first set of said components determines one or more zeros of the filter's frequency response and a second set of said components determines one or more poles of the filter's frequency response, each of said first and second sets of filter components being independent of the other such that the zero(s) and pole(s) of the filter's frequency response may be selected independently. | 01-20-2011 |
20110019767 | Phase-Locked Loop Modulation - A phase-locked loop having: an oscillator for forming an oscillating output signal; a frequency divider connected to receive the output of the oscillator and frequency divide it by a value dependent on a division control signal; and a phase comparator for comparing the phase of the divided signal and a reference signal to generate a control signal, the operation of the oscillator being dependent on the control signal; the output data to form a divided signal a division ratio controller configured to, when clocked by an input signal, generate a series of output data for forming the division control signal; the phase-locked loop having: a first mode of operation in which the frequency divider is operable to frequency divide the output of the oscillator by a value dependent on the output of the division ratio controller; and a second mode of operation in which the frequency divider is not operable to frequency divide the output of the oscillator by a value dependent on the output of the division ratio controller, and the division ratio controller is clocked by a signal that is independent of the output of the oscillator. | 01-27-2011 |
20110025386 | Phase-Locked Loop - A loop filter for a phase-locked loop that generates an output signal having a predetermined phase relationship with a reference signal, the loop filter being arranged to control a signal generator that forms the output signal in dependence on a phase error between the output signal and the reference signal by outputting a control signal for controlling the signal generator in dependence thereon, the loop filter being arranged to form the control signal to comprise a proportional component representative of an instantaneous magnitude of the phase difference and an integral component representative of an integral of the phase difference, the loop filter comprising a proportional path arranged to receive a signal representative of the instantaneous magnitude of the phase difference and form the proportional component of the control signal in dependence thereon and an integral path arranged to receive a signal representative of the instantaneous magnitude of the phase difference and form the integral component of the control signal in dependence thereon, the proportional and integral paths being decoupled in the loop filter such that each has a transfer function relating its received signal to its respective component of the control signal that is independent of the other path. | 02-03-2011 |
20110025387 | Charge Transfer in a Phase-Locked Loop - A phase-locked loop arranged to generate an output signal having a first frequency that is a static value times the frequency of 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 to cause the output signal to have a frequency that is said static value times the frequency of the reference signal, a comparison unit arranged to compare the feedback signal with the reference signal, one or more current generators arranged to output current pulses in dependence on said comparison, a summation unit arranged to receive the current pulses output by the current generator(s) and form a single current pulse therefrom and a loop filter arranged to filter the single current pulse to form a control signal for controlling the signal generator, the phase-locked loop being arranged such that the current generator(s) generate(s) a first current pulse dependent on a phase-difference between the feedback signal and the reference signal and a second current pulse whose magnitude and sign are dependent on an error in the feedback signal that is caused by the variation of the divisor, and the summation unit receives the first and second current pulses and stores an electrical charge representative of those current pulses and the summation unit outputs a single current pulse dependent on the electrical charge stored by the summation unit, said single current pulse being representative of a phase-difference that would have existed between the reference signal and the feedback signal if the feedback signal had been formed by dividing the output signal by said static value and not by the varied divisor. | 02-03-2011 |
20110025388 | Charge Pump For Phase-Locked Loop - A current generator for a phase-locked loop arranged to generate an output signal having 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 output a first error signal indicative of the phase-difference between the feedback signal and the reference signal to the current generator and a loop filter arranged to filter a current signal output by the current generator to form a control signal for controlling the signal generator, the current generator being capable of receiving the first error signal and generating a current in dependence thereon, receiving a second error signal indicative of an error in the feedback signal caused by the variation of the divisor by which the output signal is divided and generating a current having a magnitude and sign that is dependent on that error and combining the currents generated in dependence on the first error signal and the second error signal to form a current signal output to the loop filter that is representative of an overall error in the output signal of the phase-locked loop relative to the reference signal. | 02-03-2011 |
20110204938 | Charge Pump For a Phase-Locked Loop - A charge pump circuit for connection to another circuit via an output node ( | 08-25-2011 |
20130093483 | Dual Phase Detector Phase-Locked Loop - 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. | 04-18-2013 |
20140050289 | Phase-Locked Loop Modulation - A phase-locked loop having: an oscillator for forming an oscillating output signal; a frequency divider connected to receive the output of the oscillator and frequency divide it by a value dependent on a division control signal; and a phase comparator for comparing the phase of the divided signal and a reference signal to generate a control signal, the operation of the oscillator being dependent on the control signal; a first mode of operation in which the frequency divider is configured to operate in dependence on a first division control signal such that the resultant oscillating output signal has a first frequency and first phase, a second mode of operation in which the frequency divider is configured to operate in dependence on a second division control signal such that the resultant oscillating output signal has a second frequency and second phase, the first division control signal being generated independently of the oscillating output signal such that the first phase is maintained when the phase-locked loop is operating in a second mode. | 02-20-2014 |