A demodulator demodulates an in-phase component of an input signal which is in-phase and quadrature modulated. The demodulator includes a register storing a phase calibration value having an integer part and a fractional part. A noise-shaping modulator generates a succession of quantized values of integer type, the quantized values having a mean equal to the phase calibration value. A generating stage generates a demodulating signal phase locked with the input signal, the demodulating signal having a phase which depends linearly on the quantized values. A demodulating stage demodulates the input signal by means of the demodulating signal.