In accordance with the present disclosure, a personal hygiene device has a resonant motor and a motor control unit for applying a periodic voltage signal with a driving frequency at the resonant motor for driving the resonant motor into an oscillating motion with an oscillating frequency equal to the driving frequency. The motor control unit comprises a synthesizer circuit for digitally synthesizing the periodic voltage signal from voltage pulses of variable length provided with a pulse frequency higher than the driving frequency such that at least two voltage pulses are applied at least in one of two half cycles of each period of the periodic voltage signal.