High power, high conversion gain frequency doublers using SiC MESFETs and AlGaN/GaN HEMTs

High power, high conversion gain microwave frequency doublers using wide bandgap semiconductor devices are developed. A method of determining the optimal harmonic terminations using accurate nonlinear computer models and load- and source-pull simulations is described. Synthesis of these impedances using matching and reflector networks have produced doublers with increased output power, conversion gain and very high suppression of the first and third harmonics. A SiC MESFET-based frequency doubler at fo=2.00GHz producing up to 10.00dB conversion gain and 6.31 Watts 2fo output power is presented. An AlGaN/GaN HEMT-based frequency doubler at fo=3.33GHz producing up to 14.80dB conversion gain and 4.14W 2fo output power is also presented. The second harmonic power measurements confirm the accurate predictions made by the nonlinear model.