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An improved direct parameter extraction method of SiGe heterojunction bipolar transistors (HBTs) for the vertical bipolar intercompany (VBIC)-type hybrid-π model is developed. All the equivalent circuit elements are extracted analytically from S-parameter data only and without any numerical optimization. The proposed technique of the parameter extraction, differing from the previous ones, focuses on correcting the pad de-embedding error for an accurate and invariant extraction of intrinsic base resistance (Rbi), formulating a new parasitic substrate network, and improving the extraction procedure of transconductance (gm), dynamic base-emitter resistance (rπ), and base-emitter capacitance (Cπ) using the accurately extracted Rbi. The extracted parameters are frequency-independent and reliable due to elimination of any de-embedding errors. The agreements between the measured and model-calculated data are excellent in the frequency range of 0.2-10.2 GHz over a wide range of bias points. Therefore, we believe that the proposed extraction method is a simple and reliable routine applicable to the optimization of transistor design, process control, and the improvement of VBIC compact model, especially for SiGe HBTs.
Date of Publication: Mar 2005