Green´s function concept for noise model of microwave FET analysis

The main step in noise analysis of microwave FET, as an active element, is to apply a proper noise model, suitable to its high frequency structure. Noise modeling of MM-wave FETs has been studied recently by some research groups, using sliced or semidistributed modeling. In their studies, the gate-width has been divided into some slices in which the ratio of guided wave length to slice width is small. Then for each slice, a classical lumped model is defined to analyze the device noise performance. We have proposed a three-coupled excited Transmission Line (TL) structure as a new noise model of the FET. In this model the Laplace transformation was applied to determine the noise performance of the transistor device. Now we introduce a wave approach, relying on the Green´s function concept, to analyze the model. The proposed wave analysis has been applied here to analyze a general purpose MESFET. Some noise parameters of the transistor are plotted here to prove the reliability and the ability of our proposed approach in a complete noise analysis of microwave FETs