A GaAs SDFL three input NOR gate was fabricated using mesa etching isolation and recess etching method. It consists of three MESFET's of which gate length are all 2.5㎛ and width are 50㎛, 35㎛ and 15㎛ respectively and three schottky diodes of which area are 100㎛*10㎛ respectively. DC transfer characteristics of the fabricated SDFL inverter showed very high noise margin at moderate power consumption. With supply voltage of VDD=5V and VSS=-3V the noise margin is 2.25V for both high and low. AC performance measurement was carried under the condition that microprobe was directly contacted to the wafer pad. Then each pad was connected to VDD, VSS and ground port of HP 4145B, oscilloscope and pulse generator through coaxial lines. With 100kHz input pulse, good output pulse was observed but, with 1MHz input pulse, distorted output pulse was obtained. Through measurement of delay due to microprobe and coaxial lines and SPICE simulation, the fact that all delays contained in output pulse was resulted from measurement system was confirmed.
