There are two models dedicated to bipolar transistors. Mextram is the model intended for use with vertical bipolar transistors (both NPN and PNP). Its intrinsic model is basically one-dimensional, but the the model includes descriptions for the extrinsic regions and for the substrate (the fourth terminal). The intrinsic model includes quite advanced descriptions for the collector epilayer and for modern SiGe transistors.

Modella is intended for use with lateral PNP transistors. Its basic description is less advanced, but it has unique features to describe the two-dimensional current spreading effects in lateral bipolar transistors.

For the description of bipolar transistors in special processes with lateral drift regions Mextram or Modella can be used in conjunction with one of the High-Voltage Models.

The following bipolar models are available:

• Mextram for vertical bipolar models; and
• Modella for lateral PNP models;