High-speed integrated logic with GaAs MESFET´s

The feasibility of using GaAs metal-semiconductor field-effect transistors (GaAs MESFET´s) in fast switching and high-speed digital integrated circuit applications is demonstrated. GaAs MESFET´s with 1-μm gate length are shown to have a current-gain-bandwidth product f/SUB T/ equal to 15 GHz. These devices exhibit a 15 ps internal delay in a large-signal switching test. A simple logic circuit consisting of MESFET´s and Schottky diodes was monolithically integrated on a semiinsulating GaAs substrate. This logic circuit exhibits a propagation delay of 60 ps with no output load, and 105 ps when its output is loaded by three similar logic gates. A useful bandwidth of approximately 3 GHz is observed.