Full characterization of microwave low-noise packaged HEMT's: measurements versus modeling

The performance of low-noise microwave transistors is completely characterized by their scattering and noise parameters. The determination of the noise parameters requires a dedicated measurement system which is completely different from a scattering parameter measurement set up since the two parameter sets are classically treated as independent data sets. From our viewpoint, these two parameter sets are strictly related to each other and we have previously presented a unique experimental procedure that allows the determination of all the noise, gain, and scattering parameters of active devices from noise figure measurements only. We employ here a new technique for determining the noise parameters of packaged HEMT's by simply measuring the scattering parameters and the noise figure at the fixed source impedance of 50 /spl Omega/. Comparison between the two noise parameter sets derived by following both the above procedures is reported supporting the inherent consistency of the theoretical approach and the accuracy of the experimental data.