A glimpse on behavioral modeling technology for microwave transistors

Although many generations of microwave transistors have continuously fed a never ending effort of both physical and equivalent circuit device modeling, many microwave engineers have recently turned their attention to behavioral modeling. Behavioral models are measurement-based mathematical representations of the observable inputoutput characteristics of devices, regardless of their technology or of their internal composition. Therefore, not only they protect the intellectual property of the device´s manufacturer, as they are only limited by the available laboratory measurement based capabilities. Unfortunately, they also require a great deal of ingenuity in the model formulation and their predictive capability is generally worse than the one of physics-based models. The aim of this paper is to present an overview of microwave transistor behavioral models addressing their mathematical formulation and their laboratory parameter extraction procedures. Both time-domain and frequency-domain behavioral models are addressed, giving a particular emphasis on the implementations that have seen a wider acceptance.