Modeling and design of GaAs MESFET control devices for broad-band applications

Closed-form expressions are developed for the small-signal parameters of broadband GaAs control MESFETs. The theoretical conducting-state resistance and nonconducting-state capacitance are compared with experimental data and demonstrate the usefulness of the models. Additionally, the power-handling capability of these devices is considered and the various limitations in both conducting and nonconducting states are described. The models show that self-aligned-gate devices (SAGFETs) have a broadband cutoff-frequency figure of merit as much as twice that of conventional MESFETs, although the voltage-handling capability of the SAGFET is considerably inferior.>