An eight-terminal Kelvin-tapped bipolar transistor for extracting parasitic series resistances

A novel DC method for determining the components of series resistance in bipolar transistors is presented. As a DC technique, it shows unprecedented accuracy as demonstrated by its application to both metal-contacted heterojunction transistors and more conventional bipolar junction transistors (BJTs). The measurement error was minimized by using a single double-base Kelvin-tapped transistor to extract all components of series resistance. This extraction technique was applied to transistors from an industrial poly-contacted BJT process with various geometries. The authors describe the theory and application of this extraction technique in both its simplified form, where the emitter resistance is assumed to be lumped and bias-independent, and in its more general form, where it includes the distributed nature of both the emitter and the intrinsic base resistances. An exact expression for the DC and AC bias-dependent intrinsic base resistance and a methodology for calculating effective resistances for bipolar devices are presented.<
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