Measuring and fitting of the small signal model of the MOS transistor for high frequency applications

A small-signal model of a MOS transistor, valid at frequencies around the unity gain frequency, f_T, is presented. As opposed to earlier models, it takes into account the non-quasi-static and transmission-line effects of the transistor. By using computer-controlled calibration of the test setup and network analyzer, mathematical transformations, and fit routines, all the AC parameters can be calculated from the measured S-parameters. The design of high-frequency conductance amplifiers shows that the model and measurement method are accurate at frequencies up to 3F_T