The Mextram model gives an excellent description of vertical bipolar transistors in all kinds of processes, amongst which are modern SiGe processes and robust HV processes. It is very efficient in modelling the lowly doped collector epilayer of a bipolar transistor where effects like velocity saturation, base widening, Kirk effect, and impact ionisation play a role. Effects due to having Germanium in the base are also modelled. Furthermore, it contains a full description of the extrinsic regions of a transistor, including substrate current and capacitance. Mextram has formulations for temperature scaling and is easily scalable over geometry. Mextram, level 504, includes full self-heating, in contrast to having self-heating handled by the circuit-simulator. Self-heating is completely implemented in the source code.
The models are included in a dynamically loaded library called SiMKit. SiMKit is related to the following circuit simulators used within NXP®:
- Pstar, the circuit simulator from NXP
- Spectre, the circuit simulator from Cadence
- ADS, the circuit simulator from Agilent
You can read how to download and install the libraries here.
For more details on Mextram, click here