Two-dimensional distributed base-resistance effects in bipolar transistors

One-dimensional transistors are well-understood today, and computer techniques for detailed analysis are available. This paper gives a contribution to the analysis of lateral effects, especially for transistors which are of neither ring-dot nor long narrow stripe geometry. The effects of distributed capacitance and base resistance on the small-signal behavior of the transistor are modeled by a two-dimensional leaky transmission line, with different RC constants in the active and passive base regions. Computer techniques are presented for solving this problem for arbitrary emitter and base contact geometries. The use of a boundary method, rather than the conventional grid method, is particularly attractive for complicated geometries and makes possible very short computation times (typically a few seconds). The calculated h-parameters are compared to experimental data for a high-frequency, double-diffused silicon transistor.