Overview of noise measurement strategies for the characterization of active devices at microwave frequencies

The microwave noise parameters of a device can be: (a) extracted from noise figure measurements and appropriate data processing techniques, (b) obtained by a direct search of the minimum noise condition, (c) computed by a noisy circuit model determined on the basis of scattering parameter measurements and a single noise figure measure. In the present paper we review the topical aspects of these different noise characterization techniques and evaluate them comparatively from the viewpoint of the device type under test (either bipolar or field-effect transistor) on the basis of the experimental results obtained in our lab