A new characterization technique of "Four hot S parameters" for the study of nonlinear parametric behaviors of microwave devices

This paper presents a new characterization system which enables calibrated "Hot S parameter" measurements of power transistors in a load pull environment. The device under test (DUT) is driven by a large signal at a frequency f/sub 0/ while a small signal at a frequency f is injected as a perturbation signal. A frequency sweep of the perturbation tone is performed (basically from 300MHz up to f/sub 0/ (ie lower sideband)). Upper sideband, from f/sub 0/ up to 2f/sub 0/, can be extended in a same manner. The four "Hot S parameters" measured at f are dependent on the nonlinear regime of the DUT forced by the large signal at f/sub 0/. The aim of this experimental purpose is to investigate nonlinear parametric behaviors like nonlinear stability. A description of the proposed measurement set-up is done. Calibration and measurement procedures are described and significant S band measurement results of HBTs are reported and discussed.