Mextram
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

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

Simucad 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 is part of the SmartLib product-independent model library. It 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. 101807_04