AlGaAs/GaAs HBT OR /NOR gate, which can be used for high speed digital system, was designed. Equivalent circuit parameters of HBT were obtained from Gummel-Poon'smodel and direct extraction method. Simulations results with PSPICE showed that propagation delay time and cutoff toggle frequency of designed gate were 25ps and 20GHz, respectively. the designed gate exhibited superior properties to the recently reported HBT ECL and MESFET SCFL when considering the fan-out characteristics and noise margin.