Comments on "A compact physical large-signal model for high-speed bipolar transistors at high current densities-part I: one-dimensional model" (by H.-M. Rein et al., with reply)

The junction space-charge-region capacitances are of primary importance for high-speed VLSI bipolar circuit modeling. It is shown in the above paper that the emitter-base junction capacitance model is compact and is in excellent agreement when compared with other relatively complicated models and methods. However, the base-collector junction capacitance model is questionable in the sense that the base-collector junction capacitance becomes more important, rather than being negligible, as suggested by Stubing and Rein, in the high current region. In reply, Rein et al. show that their model is admissible, and give some remarks on Liou´s additional comments. Since the transistor model was developed for high-speed ICs, the numerical examples presented are typical for such circuits. This means, e.g., that the specific resistances and the effective thicknesses of the epitaxial collector are more than about ten times lower than in the example given by Liou.<>