Extraction of base and emitter series resistances from the net transadmittance parameter

We report a new high-frequency technique for extracting base and emitter resistances (R/sub bb/ and R/sub e/, respectively) of a bipolar junction transistor. We highlight, for the first time, the physical significance of the net transadmittance parameter (y/sub 12/-y/sub 21/) as a figure of merit for the transistor's intrinsic performance. We report that while Real(y/sub 12/-y/sub 21/) increases monotonically with frequency, Imag(y/sub 12/-y/sub 21/) exhibits a peak in the GHz range. This peak is attributed to competition between the obstruction of signals as a result of the base-collector capacitance, and the shunt path to ground. We have proven, both theoretically and experimentally, that -1/Real(y/sub 12/-y/sub 21/) is linearly proportional to /spl omega//sup 2/ with a y-intercept of 1/g/sub m/+R/sub e/+R/sub bb///spl beta//sub dc/. By combining this result with the Basaran-Berroth method, individual values of R/sub e/ and R/sub bb/ are extracted and plotted as a function of V/sub be/. Data from transistors with various emitter lengths further validate the efficacy of this extraction technique.