Abstract: Novel equations in terms of the current of the intrinsic collector and emitter are implemented to improve the fitting ability of a III-V compound HBT model.An equivalent circuit for the HBT under zero- and cold-bias conditions is proposed for the extraction of access resistances and parasitic inductances.In order to determine the intrinsic and extrinsic parts of the base-emitter,base-collector junction capacitances accurately,a novel direct parameter-extraction method based on "cold-bias" S-measurements is developed.After directly extracting the intrinsic collector resistance Rci,this method describes how to extract the intrinsic and extrinsic capacitances from different "cold bias" points.Experimental validation on a GaAs HBT device with a 180μm2 emitter is carried out,and excellent results are obtained up to 40GHz.

Key words: III-V group, HBT model, cold-bias,  intrinsic and extrinsic junction capacitances, intrinsic collector resistance, direct extraction