Automated characterization of HF power transistors by source-pull and multiharmonic load-pull measurements based on six-port techniques

An original measurement system for nonlinear microwave power-transistor characterization using six-port reflectometers is presented. It allows independent active tuning of the output impedances at f ₀ and 2f ₀ (multiharmonic load-pull) and variation of the source impedance at the input port at f ₀ (source-pull). An appropriate search algorithm enables automatic optimization of the output impedances and leads to fast user-friendly operation of the system. Experimental results are shown for a commercial GaAs MESFET power transistor at f ₀=2 GHz.