Traveling-wave inverted-gate field-effect transistors: concept, analysis, and potential

A unified approach to the analysis of the traveling-wave inverted-gate FET (INGFET) is presented. The equivalent circuit parameters of the GaAs inverted-gate FET, with submicrometer gate length, are obtained using a two-dimensional computer model which takes into account the nonstationary electron dynamics. The parameters of the passive transmission line, corresponding to the INGFET structure, are obtained using a quasi-transverse-electromagnetic (TEM) wave approach. The conductor losses of this structure are estimated using the incremental inductance rule. The coupled mode theory is used to derive the wave equation describing this traveling-wave transistor. The results show the existence of a rapidly growing mode along the device electrodes. It is also shown that this mode can be excited alone by appropriate matching and feeding arrangements. Improper matching and feeding lead to a narrower bandwidth due to the resonance phenomenon of the resulting standing wave