Power amplifier characterization: an active load-pull system based on six-port reflectometer using complex modulated carrier

An original measurement system for nonlinear RF power-transistor characterization is presented. This new setup enables measurement and optimization of output power, power added efficiency (PAE) or linearity using active fundamental tuning and six-port reflectometers as vector network analyzers. High and low frequency bias-Tees are inserted at both ports of transistors in order to control source and load impedances at the base-band (envelope) frequency. Experimental results at 1.575 GHz, show an ACPR improvement of 20 dB for a commercial GaAs MESFET power transistor.