A radio-frequency power amplifier is supplied by a voltage supply device. The voltage supply device has a voltage divider chain that is connected at the input side with a base potential and a ground voltage. The voltage divider chain has a number of Zener diodes connected in series, with which at least one capacitor is connected in parallel. Intermediate voltages that lie between the ground voltage and the base potential can be tapped at respective node points between each two immediately adjacent Zener diodes. A first supply input of the radio-frequency power amplifier is connected with the ground voltage. The voltage divider chain is connected with the radio-frequency power amplifier via a switching device. The switching device has a number of switching elements connected in parallel with one another, these switching elements being connected at the output side with a second supply input of the radio-frequency power amplifier. The base potential or one of the intermediate voltages is present at the input side of each switching element. The switching elements can be individually controlled by a control device, such that the second supply input can be selectively connected with the base potential and each of the intermediate voltages via the switching device.