Power efficiency and loss in push-pull MOS-FET DC-to-RF power inverter for plasma generator

This paperdescribes the power efficiency and losses in push-pull MOS-FET arrays in an inverter for a plasma generator. The inverter consists of parallel connected MOS-FETs and the output powertransformer. The power losses within the MOS-FET arrays and output power transformer are estimated based on their thermal resistances, which were obtained separately by measurements. The drain efficiency was thus obtained from the DC input power, RF output power, and estimated power losses. The output power of the MOS-FET arrays was 1 kW, with a drain efficiency of 79% and at 13.56 MHz, when the DC voltage was 48 V.