Method to determine intrinsic and extrinsic base-collector capacitance of HBTs directly from bias-dependent S-parameter data

This letter presents a novel small-signal model extraction procedure which determines intrinsic and extrinsic base-collector capacitance (C/sub bci/ and C/sub bex/, respectively) directly from S-parameter data. The procedure utilizes physical assumptions shout the bias dependence of small-signal parameters. The model is validated on several InGaP/GaAs HBTs with different layouts, and the extraction results are discussed. The small-signal model is physical, produces excellent S-parameter fits, and may be used to derive a compact large-signal model.