A pulse width modulator for modulating a rectangular carrier signal in accordance with an input signal includes a modulating unit that receives the input signal and provides a digital output word. The output word has a pre-defined number of digits comprising a first contiguous set of binary ones (“1”) and a second contiguous set of binary zeroes (“0”) and in which the fraction of the binary ones (“1”) represents the digital input signal. The modulator also includes a random number generator that generates a pseudo-random sequence, and a flipping unit configured to flip, or not, the output word provided by the modulating unit in accordance with the pseudo-random sequence thus providing a randomly modified digital pulse width modulated output signal.