Load error correction for high power load dependent X-parameter measurements

Models for active devices operating in a nonlinear regime are an indispensable tool for modern RF-circuit design. A popular class of large signal models are X-parameters which offer an accurate description of nonlinear devices. However, they require a specialized measurement setup. Typically nonlinear vector network analyzers (NVNA), are used to conduct the measurements required for an X-parameter model. In their standard configuration, these instruments cannot cope with the high power levels and typical impedances demanded by practically relevant nonlinear devices. So the test-set of an NVNA must be adapted, and tuners have to be added to manipulate the load condition. However, these additional components also add imperfections. This work elaborates how undesired port-mismatch induced by the tuners, and the resulting imperfect stimuli, as well as the corresponding systematic errors in the parameter extraction can be tackled. It explains how the imperfect stimuli can be characterized alongside standard measurements, which allows to correct systematic errors in the parameter extraction. Finally, this work compares the accuracy of this correction for a nonlinear circuit model as well as for a measured device.