Power loss and efficiency in full-bridged MOS-FET DC-to-RF Power Inverter with Output Power of 1kW at 2.5MHz

This paper describes the power loss and efficiency in full-bridged MOS-FET arrays, each consisting of parallel connected MOS-FETs, and those in an output power transformer whose output power is fed to a load at an output power of 1kW at a frequency of 2.5MHz. The power losses within the MOS-FET arrays and output power transformer are estimated based on their thermal resistances which have separately been obtained from the measurement. The drain efficiency is thus obtained from the DC input power, RF output power, and estimated power losses. The output power of the MOS-FET arrays was 1300 to 1400W at a drain efficiency of 74 to 79% at a frequency of 2.5MHz when the DC voltage was 180V.