US Patent 7214934 Radio frequency power generator

A RF power generator for exciting inductively coupled plasma for spectrometry includes an induction coil for exciting the plasma as part of its load circuit. The load circuit also comprises a capacitor connected in parallel with the induction coil. The RF power generator is a free running oscillator having a switching circuit of two MOSFETs alternately switchable on and off via a feedback control circuit from the load circuit. RF power from the switching circuit is coupled to the load circuit via an inductor. The inductor and load circuit is resonant at a first frequency, which is lower than the operating frequency of the power generator.