Basic expressions and approximations in small-signal parameterextraction for HBT's |
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Authors: | Li B Prasad S |
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Affiliation: | Dept. of Electr. & Comput. Eng., Northeastern Univ., Boston, MA; |
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Abstract: | Basic expressions and approximations used to extract small-signal parameters for heterojunction bipolar transistors or bipolar junction transistors are developed in this paper. A T-type small-signal equivalent circuit after deembedding the pad capacitances is used for the derivation. The relative magnitudes of ωRbcCbe , ωRbiCbc, and ωrcC bell were used to evaluate the frequency ranges. Fully numerical or partially numerical approaches can be developed by these approximations. An element parameter-extraction procedure is also given in this paper. Two special cases (“cold” bias and degrading equivalent circuits) are also discussed |
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