The extraction of the model elements of an equivalent circuit for a microwave FET is commonly based on the measured scattering coefficients of different operating conditions and additional data fromDC measurements. This paper discusses new modelling approaches involving only ‘hot’ S-parameters with respect to the device operating point. It is shown that regarding the hitherto attainable measurement accuracy, both the presented statistical optimizer based and analytical extraction method need the knowledge of one of the parasitic resistances, e.g.,R g , for satisfying extraction results.