The high frequency-surgical appliance has a high frequency generator, which generates a high-frequency output signal (a1) for treating, particularly for cutting or coagulating of biological tissue. The high frequency-generator is designed such that its output signal has a predetermined fundamental frequency. A modulation device is provided for modulating the output signal with the modulation frequency. The modulation frequency is lesser than the fundamental frequency, particularly 100 kilohertz. The output signal is modulated by a pulse-width modulation. An independent claim is included for a method for operating a high frequency-surgical appliance.
