In the case of a power supply device (2) for an electric circuit (3), an energy source (4) and an electric filter (7) are provided for the reliable and low-emission supply of energy to the electric circuit (3), wherein the energy source (4) and the electric filter (7) interact in such a way that the power supply device (2) has, at a filter output (9), a voltage source characteristic in a first frequency range and a current source characteristic in a second frequency range, which has a higher frequency than the first frequency range.