Enhanced voltage silicon metal-semiconductor-field-effect-transistors (MESFETs) have been fabricated on a 45nm SOI CMOS technology with no process changes. MESFETs scaled to L g = 184nm were fabricated and show a peak f T of 35GHz, current drive of 112mA/mm and breakdown voltages exceeding 4.5V whereas the nominal CMOS voltage was less than 1V on the same process. The devices were characterized from DC to 40GHz and an industry standard TOM3 model has been developed describing their operation. A board level Class AB power amplifier operating at 433MHz was designed, fabricated and measured to have a peak output power of 17dBm and peak PAE of 42.5%. The supply voltage of the PA was more than twice the breakdown voltage of corresponding CMOS on the same semiconductor process. The measured PA results were used to validate the model across different bias and input power level conditions.