Small-signal, high-frequency theory of field-effect transistors

In this theory a field-effect transistor of planar geometry is considered as an active, distributed, nonuniform transmission line. The wave equation of this line is determined and solved by an approximation method. From this solution the parameters are determined. By comparing the results for y11with van der Ziel\´s expression for the high-frequency gate noise of field-effect transistors, it is shown that the noise temperature of y11is of the order of the device temperature. The conductance part g11of y11varies as ω²over a wide frequency range. The high-frequency cutoff of the field-effect transistor is determined.