Fast direct procedure for noise characterization of microwaves transistors (HEMTs)

To derive the four noise parameters of a microwave device the conventional methods require different measures of the noise figure at different input termination conditions in order to allow averaging and to ensure a unique solution. By these methods, however, it is impossible to measure directly the optimum term Fo, |Γ_o| o, /Γ_o that can be only determined by final computation as a part of the four parameters. In the present paper a computational method is described for measuring on-line the real noise figure minimum of the device under test. This method is very fast and overcomes some drawbacks of the conventional ones