An Analytical Approach for Extraction of Extrinsic HBT Parameter by Accurately Accounting the Distributed Nature of Base Resistance
Muhmmad Shah Alam and George Alastair Armstrong
An improved small-signal equivalent circuit model of a HBT including extrinsic resistance, inductance, capacitance and substrate parasitic is presented. The major issue discussed is the importance of paying detailed attention to accurate de-embedding of the many parasitic elements, in order to be able to accurately extract model parameters for the intrinsic transistor. When dealing with the intrinsic transistor a new method of separating base resistance into and extrinsic and intrinsic components is explained and appropriate analytical expressions are derived. The parameter extraction scheme is shown to be valid over a wide range of bias conditions and gives an excellent match to measured S-parameters from 0.25–26.5 GHz.
Keywords: GaAs HBT, Extrinsic parameter extraction, Analytical approach, Small signal modeling.