In an impedance matching circuit selectively operable in a normal matching mode and a protection mode, the impedance matching circuit includes a set of reactances in a first reactance arrangement configured to transform an impedance of a load to an impedance within a range of a nominal impedance of an HF generator in the normal matching mode, and a PIN diode switch having a first invariable switching state in the normal matching mode and a second switchomg state that reconfigures the set of reactances into a second reactance arrangement in the protection mode, such that the second reactance arrangement is configured to transform the impedance of the load to prevent damage to the HF generator or to transmission circuitry arranged between the HF generator and the load.