A circuit (1) used for power factor correction, corresponds to a known circuit that includes a high-frequency frequency source (15) for generating a high-frequency voltage (Uf) for a pump capacitor (14). The high-frequency voltage source (15) has two on/off switches (151, 152) connected in series that generate, at an electric connection point (153), a square wave voltage (U1) that varies between these two switches with a frequency (f) of at least 1 megahertz. The voltage source further includes a smoothing device (150) for generating from the square wave voltage a smoothed voltage (Uf) for the pump capacitor, whereby the smoothed voltage varies with a frequency (f) of at least 1 megahertz.