General Purpose Bipolar Model

New Level 504 Improvements

Mextram 504 upgrdes the previous 503 version with the following features:

  • Includes self-heating, allowing device temperature to be dynamically computed. Self-heating calculations use only analytical derivatives, reducing simulation times (no need to compute numerical derivatives)
  • Modeling of SiGe is now possible, using a dedicated set of reviewed parameters wjhic makes the extraction procedure easier
  • Two constant overlap capacitances have been added
  • First and higher order derivatives have been smoothed, resulting in better accuracy and convergence ability
Evolution of cut-off frequency with smoothing parameter AXI

Forward DC characteristics


Mature Bipolar Model

Mextram provides several features that Gummel-Poon model lacks:

  • Bias-dependent Early effect
  • High injection effects
  • Ohmic resistance of the epilayer
  • Velocity saturation effects on the resistance of the epilayer
  • Hard and quasi saturation (including Kirk effect)
  • Split base-collector and base-emitter depletion capacitance
  • Substrate effects and parasitic PNP
  • Current crowding and conductivity modulation of the base resistance
  • First order approximation of distributed high frequency effects in the intrinsic base (high frequency current crowding and excess-phase shift)
  • Recombination in the base (for SiGe transistors)
  • Early effect in the case of a graded bandgap (for SiGe transistors)
  • Temperature scaling
  • Self-Heating

Silvaco Implementation

  • Mextram is compatible with VZERO and BYPASS options in order to achieve greater speed performance
  • Internal warnings and diagnostics provide valuable information to help find convergence issues
  • User-friendly parameters checking: user is kept aware of every clipped parameter
  • Device internal variables (currents, conductances, charges...) can easily be accessed like any other parameter
  • Mextram model can be accessed within SmartSpice as level 503 or 504

Advanced Applications

Mextram’s second version is now well suited to high technology:

  • Advanced processes such as double poly or even SiGe can be modeled
  • Mextram can be used for high-voltage power applications
  • Uncommon situations like simulating the NPN device in LDMOS technology behave correctly with Mextram

Rev. 012014_05