Spectral aliasing effects of PWM signals with time-quantized switching instants

This paper investigates the problem of the spectrum effects that appear in the power spectrum density (PSD) of a digitally implemented Pulse Width Modulated (PWM) signal. We recognize that as the digital implementation forces the switching instants to be time-quantized, an aliasing effect modifies the properties of the original PWM spectrum. Furthermore, we analyze, through analytical tools and numerical simulation, such effects for two typical cases: a sinusoidal modulating signal and Pulse Amplitude Modulated (PAM) carrying a maximum information modulating signal.