A modulator for a flying-capacitor type multilevel converter receives, at an input, a time-variant reference signal and provides, at an output, a sequence of target levels, to provide switching signals for switching between discrete output levels of the multilevel converter according to the shape of the reference signal. The modulator determines a critical level as an intermediate output level of the multilevel converter which is closest to the level of the reference signal; and outputs only target levels corresponding to output levels different from the critical level.