Abstract: A stabilized high-voltage power supply is disclosed, having a general setup similar to a pulse-step modulator. The power supply comprises a plurality of DC power modules (40) having their outputs connected in a series configuration. Each power module comprises a DC voltage source (41), a DC-DC converter (42), and an output switching circuit (43). The total output voltage of the power supply is regulated by regulating the DC link voltage at the output of each power module. This is achieved by an appropriate feedback control circuit driving the DC-DC converter of each power module. In this manlier, low output ripple and a rapid response to changes in output current can be achieved. The power supply may be used, e.g., as the cathode power supply of a gyrotron.