Accurate Noise Characterization of Low Noise Devices

This paper describes the use of the vector corrected noise measurements to determine the noise parameters of low noise HEMT devices. The noise parameters of low noise HEMTs were measured using the Wiltron 360 VNA, 3642A noise figure module, and the 3680 universal test fixture. The noise parameters F(min), [unk] (opt) were determined from error corrected Y factor measurements and the effects of input and output tuners were de-embedded from the device measurements. The noise parameters were derived from Y factor and S-parameter measurements. Although the 4 noise parameters of a two-port can be derived in many equivalent forms, the use of noise wave concepts is the most applicable to the measurements described in this paper. These representations are either the output noise waves at each port and their correlation or the two noise waves at the input port and their correlation. These noise waves can be easily converted to the more familiar data sheet representation of F(min), Rn, and [unk]opt. The limitations to the representation of noise parameters will be presented, and also methods of measurement.