High-Speed Enhancement-Mode GaAs MESFET Logic

High-speed enhancement-mode GaAs MESFET Iogic circuits have been fabricated by electron beam lithography. A 15-stage ring oscillator composed of 0.8-mu m gatelength and 40-mu m gatewidth inverters has given a minimum propagation delay time of 77 ps at a power dissipation of 977 mu W. A minimum power-delay product of 1.6 fJ has been obtained with a 20-mu m gatewidth circuit at a propagation delay time of 200 ps. Liquid nitrogen temperature operation has also been performed, and a speed almost twice higher than that at room temperature has been obtained. The minimum propagation delay time was 51 ps, and the associated power dissipation was 1.9 mW.