Method and a device for phase and frequency comparison

A phase and frequency comparator adapted to control the frequency of the output signal of an oscillator having a frequency control input, the comparator receiving at its input a signal (Sref) having a reference frequency (Fref) and a signal from the oscillator and comprising:

• first detection means for detecting continuously in the reference signal (Sref) and in the signal from the oscillator events representative of the frequency and the phase of the signal,
• a first source (S1+) of control signals at a first level (In),
• a second source (S1−) of control signals at the first level (In) and of the opposite polarity to the signal from the first source,
• first switching means which when closed apply to the output of the comparator the control signal from the first source (S1+) after detection of one of said events in a first signal of said reference signal and said signal from the oscillator,
• second switching means which when closed apply to the output of the comparator the signal from the second source (S1−) after detection of one of said events in a second signal of said reference signal and said signal from the oscillator, and
• first control means for controlling the first and second switching means to place them in the open state when they are simultaneously in the closed state, which phase comparator is characterized in that it further comprises:
• a third source (S2+) of control signals at a second level (In+ε),
• a fourth source (S2−) of control signals at the second level (In+ε) and of the opposite polarity to the signal from the third source,
• third switching means which, in the closed state when the first switching means are in the closed state, apply to the output of the comparator the control signal from the third source (S2+) after detection of one of said events in the first signal of said reference signal and said signal from the oscillator,
• fourth switching means which, in the closed state when the second switching means are in the closed state, apply to the output of the comparator the signal from the fourth source (S2−) after detection of one of said events in the second signal said reference signal and said signal from the oscillator, the output signal (Io) of the comparator having a level corresponding to the sum of the control signals applied by the switching means at the output of the comparator, and
• second control means adapted to place the first and second switching means the open state when the third and fourth switching means are simultaneously in the closed state.