Phase-locked loop circuit and method

A circuit, comprising:

• a phase detector configured to detect a phase difference between an input clock signal applied to a first input and a further clock signal applied to a second input;
• a charge pump configured to produce a phase-lock control signal;
• a voltage-controlled oscillator configured to produce a pulsed output signal at an output node in response to a voltage control signal;
• a feedback loop from the output node of the voltage-controlled oscillator to the second input of the phase detector, wherein said feedback loop generates the further clock signal in response to the pulsed output signal from the voltage-controlled oscillator, and
• switch circuitry configured to switch the circuit from a first circuit configuration to a second circuit configuration, wherein:
• in the first circuit configuration, said voltage control signal for the voltage-controlled oscillator is a reference voltage, and the charge pump is decoupled from an output of the phase detector and configured to regulate the phase-lock control signal at said reference voltage;
• and
• in the second circuit configuration, the charge pump is coupled to the output of the phase detector and configured to produce said phase-lock control signal based on said phase difference detected by the phase detector and the voltage-controlled oscillator is configured to receive said phase-lock control signal generated from the charge pump as said voltage control signal.