Extraction of DC base parasitic resistance of bipolar transistors based on impact-ionization-induced base current reversal

A method for the evaluation of the DC base parasitic resistance, R/sub B/, of bipolar transistors is described. The method is based on impact-ionization-induced base current reversal and enables R/sub B/ to be evaluated independently from the emitter parasitic resistance in a wide range of emitter current and collector-base voltage, without requiring any special device structure. The method can also extract R/sub B/ in the impact-ionization regime, where current crowding due to negative base current induces an increase in R/sub B/ at increasing emitter current.<
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