Procedure to derive analytical models for microwave noise performances of Si/SiGe:C and InP/InGaAs heterojunction bipolar transistors

We present a useful procedure to derive simplified expressions to model the minimum noise factor and the equivalent noise resistance of Si/SiGe:C and InP/InGaAs heterojunction bipolar transistors (HBTs). An acceptable agreement between models and measurements at operation frequencies up to 18 GHz and at several bias points is demonstrated. The development procedure includes all the significant microwave noise sources of the HBTs. These relations should be useful to model Fmin and Rn for state-of-the-art IV-IV and III–V HBTs. The method is the first step to derive noise analyses formulas valid for operation frequencies near the unitary current gain frequency (fT); however, to achieve this goal a necessary condition is to have access to HFN measurements up to this frequency regime.