Base-collector junction capacitance of bipolar transistors operating at high current densities

An analytical physics-based comprehensive base-collector junction capacitance model is presented. The model, which includes high-current effects, describes the base-collector space-charge-region capacitance for all operating regions, including the saturation region in which the space-charge region becomes forward biased. The present model is compared with the depletion capacitance model and significant discrepancies are predicted. An emitter-coupled logic gate circuit is used to demonstrate the practical usefulness of the model.