Phase locked loop having plural selectable voltage controlled oscillators

A phase-locked loop comprising:

• a phase detector for comparing the phase of a reference signal with the phase of an internal signal to produce a phase difference signal proportional to the phase difference found between the signals,
• a filter for producing a phase control signal with a voltage value proportional to the phase difference signal,
• a plurality of voltage-controlled oscillators with different mean frequencies which oscillate at a frequency controlled according to the voltage value of the phase control signal,
• a controller for switching between the oscillating state and the stopped state of each of said plurality of voltage-controlled oscillators,
• a selector for selecting one of the outputs of said plurality of voltage-controlled oscillators on the basis of the phase difference signal or the phase control signal, and
• a frequency divider for dividing the frequency of the selected output to produce said internal signal, wherein, when a phase control signal changes its voltage value, said plurality of voltage-controlled oscillators vary their output frequencies equal amounts.