Electrosurgical HF generators are often used to cut or coagulate biological tissue in modern surgery. For this purpose, an HF signal with a frequency greater than 300 kHz is produced by an electrosurgical HF generator and is applied, via an electrode, by a surgeon at the site to be treated. Electrosurgical HF generators comprise a power supply for supplying a generator stage that excites an HF oscillation in an output filter, which comprises a parallel resonant circuit and a series resonant circuit. An electrosurgical HF generator of this type is known, for example, from DE 39 04 558 A1.
A problem in the development of electrosurgical HF generators is that they have to have a very high level of efficiency. Otherwise, a cooling system, which would not be acceptable in operating theatres, would be needed for the electrosurgical HF generator; in addition, a three-phase connection must be dispensed with, if possible. Increasing the maximum current output by an electrosurgical HF generator and the maximum HF voltage is therefore only possible if the efficiency level of the electrosurgical HF generator is further improved.