Abstract: Electrosurgical generator and method for outputting a high-frequency alternating voltage to an electrosurgical instrument, including an inverter that generates a high-frequency alternating voltage having variable frequency and amplitude which is fed to an output socket for the electrosurgical instrument. Ahe inverter is a multi-level inverter controlled by a reference signal defining shape of the generated HF alternating voltage, the reference signal being defined by a datagram including a finite series of sequenced amplitude and frequency data vectors for a defined number of periods. By such datagrams including descriptive data for the desired HF sinusoidal curve, data amount and bandwidth required can be reduced. Thereby a variety of modes can be described using a minimum of data which can be as low as just a few dozen bytes long. This allows for efficient control even of complex modes.