Simultaneous extraction of the base and thermal resistances of bipolar transistors

A method for the simultaneous extraction of the base resistance R/sub b/ and thermal resistance R/sub th/ of bipolar transistors is described. The technique can be applied to single devices without the requirement of special structures. The measurements are based on the collector-base voltage dependence of the base-emitter voltage under constant emitter current steering and accounts for the influence of Early effect and self-heating. Results are obtained for advanced HBTs with several emitter widths enabling the extraction of R/sub th/ and the intrinsic and extrinsic contribution of R/sub b/. A detailed comparison is made with other extraction techniques and reveals an excellent agreement.