Systematic design approach for AlGaAs/GaAs HBT using two‐dimensional device simulator and circuit simulator

Abstract

A systematic design method for HBT's is described which is based on a two‐dimensional device simulator and a circuit simulator. The validity of this method has been studied by applying it to an AlGaAs/GaAs HBT with a base electrode sandwiched by two emitter electrodes. This structure has a performance better than that of a conventional structure. It is found that the designed values agree well with the measured results for hFE, CBE, CBC and fT. It is shown that the design accuracy of fT and CBE can be improved if the hot electron effect is introduced in the device simulator. A large signal modeling method is proposed by the circuit simulator SPICE‐F' which is modified so that the collector‐emitter offset voltage characteristic to the HBT can be expressed. By way of this new method, the bias dependence of equivalent circuit parameters of the HBT, such as fmax, fT, CBE and CBC, can be computed with good correlation with the experimental data.