NOISE MODELING OF MICROWAVE HETEROJUNCTION BIPOLAR-TRANSISTORS

Analytical expressions of microwave heterojunction bipolar transistors minimum noise figure and noise parameter are reported in this paper. These expressions are derived from a noise model including nonideal ju nctions, emitter and base resistances and have been compared with meas ured data obtained on a Si/SiGe HBT. An agreement between theoretical and experimental data was observed up to 20 GHz for several bias condi tions. The limits of the model or the range of validity of the propose d equations have been also examined with the help of an appropriate CA D software. The analysis of the influence of parasitic elements on noi se parameters has shown a strong influence of the extrinsic base colle ctor capacitance at microwave frequencies.