A spread-spectrum clock signal generator

摘要

A spread-spectrum clock signal generator (100) comprises a circuit loop (105a) receiving a reference signal (Fref) at a reference frequency and adapted to generate an output signal (Fout) at an output frequency dependent on and locked to the reference frequency, and a modulator circuit (145) generating a modulation signal (Im) at a modulation frequency; the modulation signal is injected into the circuit loop to induce a modulation of the frequency of the output signal with respect to the frequency dependent on the reference frequency. The circuit loop is a frequency-locked loop and has a bandwidth sufficiently higher than the modulation frequency, so that the output frequency tracks the modulation signal. Frequency-offset correction means (105b) are further provided, for evaluating a frequency offset between an average frequency of the output signal and the frequency dependent on the reference frequency, and for generating a frequency-offset correction signal (I2) which is injected into the circuit loop for correcting the evaluated frequency offset. <IMAGE>