Nonlinear transmission-line model of an FET terahertz detector for arbitrary gate voltage

In this paper, a dynamic nonlinear transmission-line model for a field-effect transistor (FET) is proposed. The model can be used for a field-effect transistor operating as a detector of terahertz waves. Plasma wave excitation and rectification in the channel of a zero drain-source biased FET enables terahertz-wave detection. The terahertz response of the FET can be predicted by solving the telegrapher´s equations inside the transistor channel at an arbitrary gate voltage and under non-resonant conditions. At room temperature, the influence of gate voltage on the detector responsivity is investigated. Moreover, the effect of gate bias voltage on the internal equivalent noise power and on the detector responsivity is studied for a typical Si FET.