A circuit for processing a supply voltage with a voltage peak to obtain an output signal with reduced or eliminated voltage peak, comprises a first capacitance and a second capacitance, wherein a controllable resistor is formed between the first and second capacitance in series to the same, which has a high resistance when a voltage at the first capacitance is smaller than an input voltage set value, and whose resistance is reduced to a lower resistance when the input voltage at the first capacitance is higher than or equal to the input voltage set value, so that finally, when the output voltage at the second capacitance reaches an output voltage set value, the controllable resistor is substantially no longer visible, but connects the two capacitances in parallel. The circuit is particularly advantageous as filter capacitance in a switching regulator, to achieve fast starting up of the switching regulator on the one hand and, on the other hand, simultaneously, fast charging of the second capacitance, wherein the energy of the voltage peak is used for charging the second capacitor more quickly.