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Mextram 504 BJT Model (504.10): MXTRM



The Cadence® MXTRM element is the successor of MXTR504, and implements the entire family of Philips Mextram level 504 devices (bjt504, bjtd504, bjt504t, and bjtd504t). MXTRM works as a single entry point to a growing family of Verilog-A defined component models. The appropriate Verilog-A defined component is selected depending on what you specify, for example, version, self-heating support, or substrate support. Version 504.10 is the latest version supported by this model.

The Philips Mextram model provides an excellent description of vertical bipolar transistors in all types of processes, including modern SiGe processes and robust HV processes. It is very efficient in modeling the lowly-doped collector epilayer of a bipolar transistor where effects like velocity saturation, base widening, Kirk effect, and impact ionization play an important role. Effects resulting from the presence of Germanium in the base are also modeled. 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 supports full self-heating.

See the Philips model website[1] for complete documentation and Verilog-A definition of component models.


Only primary parameters are shown. Secondary parameters follow the Mextram 504 specification/standard.

Name Description Unit Type Default
ID Element ID Text MX1
VERSION Model version   504.10
TYPE Device type   npn
SELFT Self-heating support   off
SUBS_NODE Substrate node support   on
TNOM Reference (extraction) temperature Temperature 25DegC
TEMP Simulation temperature Temperature _TEMP
MULT Number of devices in parallel   1.0

Operating Points

You can access operating point information, as defined by the active Verilog-A based component model.

Implementation Details

The TYPE parameter controls whether the device is NPN or PNP, and the SUBS_NODE parameter enables/disables (on/off) substrate support. The SELFT parameter enables/disables the self-heating modeling capabilities. The current setting of any of these parameters is reflected by the device symbol. The extraction and simulation temperatures are controlled using the TNOM and TEMP parameters respectively; instead of TR and DTA. Parameter default and truncation values are identical to those employed by Philips.


This element does not have an assigned layout cell. You can assign artwork cells to any element. See “Assigning Artwork Cells to Layout of Schematic Elements” for details.


[1] http://mextram.ewi.tudelft.nl/

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