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_bb and R_e, respectively) of a bipolar junction transistor. We highlight, for the first time, the physical significance of the net transadmittance parameter (y₁₂-y₂₁) as a figure of merit for the transistor´s intrinsic performance. We report that while Real(y₁₂-y₂₁) increases monotonically with frequency, Imag(y₁₂-y₂₁) 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(y₁₂-y₂₁) is linearly proportional to ω² with a y-intercept of 1/g_m+R_e+R_bb/β_dc. By combining this result with the Basaran-Berroth method, individual values of R_e and R_bb are extracted and plotted as a function of V_be. Data from transistors with various emitter lengths further validate the efficacy of this extraction technique.