There is no replacement for this OBSOLETE element. The Mextram model was developed as a general-purpose BJT model for use throughout the electronics industry. Mextram was developed at Philips, and the Cadence® AWR® Microwave Office® software model is a full implementation of Philips' Mextram 503 model. Mextram models a large variety of effects that are not included in the SPICE Gummel-Poon model; these include weak avalanche effects, hard- and quasi-saturation, hot-carrier effects in the epilayer, and substrate current. It includes improved temperature scaling, but not self-heating.
Name | Description | Unit Type | Default |
---|---|---|---|
ID | Element ID | MX1 | |
*NPN | NPN (flag, information only) | 1 | |
*PNP | PNP (flag, information only) | 0 | |
*Release | Release (information only) | 503 | |
EXMOD | Flag for extended modeling of reverse current gain | 1.0 | |
*EXPHI | (Not implemented) | 0.0 | |
EXAVL | Flag for extended modeling of avalanche currents | 0.0 | |
*IS | Collector-to-emitter saturation current | Amperes | 5e-14 |
*BF | Forward current gain | 140.0 | |
*XIBI | Fraction of ideal base current from sidewall | 0.0 | |
*IBF | Saturation current of the non-ideal forward base current | Amperes | 2e-14A |
*VLF | Cross-over voltage of the non-ideal forward base current | Voltage | 0.5V |
*IK | High-injection knee current | Amperes | 15.0e-3A |
*BRI | Ideal reverse current gain | 16.0 | |
*IBR | Saturation current of the non-ideal base current | Amperes | 8e-15A |
*VLR | Cross-over voltage of the non-ideal reverse base current | Voltage | 0.5V |
*XEXT | Parameter dependency of VBC1 | 0.5 | |
*QBO | Base charge at zero bias | 1.2e12 | |
*ETA | Factor of the built-in field base) | 4.0 | |
*AVL | Weak avalanche parameter | 50.0 | |
*EFI | Electric field intercept | 0.7 | |
*IHC | Critical current for hot carriers | A | 3.0e-3 |
*RCC | Constant part of the collector resistance | Resistance | 25.0 ohm |
*RCV | Resistance of the unmodulated epilayer | Resistance | 750.0 ohm |
*SCRCV | Space charge resistance of the epilayer | Resistance | 1000.0 ohm |
*SFH | Current spreading factor epilayer | Resistance | 0.6 ohm |
*RBC | Constant part of the base resistance | Resistance | 50.0 ohm |
*RBV | Variable part of the base resistance at zero bias | Resistance | 100.0 ohm |
*RE | Emitter series resistance | Resistance | 2.0 ohm |
*TAUNE | Minimum delay time of neutral and emitter charge | Conductance | 0.3e-9s |
*MTAU | Non-ideality factor of the neutral and emitter charge | 1.18 | |
*CJE | Zero bias BE depletion capacitance | Faraday | 0.25e-12F |
*VDE | BE built-in voltage | Voltage | 0.9V |
*PE | BE grading coefficient | 0.33 | |
*XCJE | Reaction of BE capacitance to the sidewall | 0.5 | |
*CJC | Zero bias BC depletion capacitance | Faraday | 0.13e-12F |
*VDC | BC built-in voltage | Voltage | 0.6V |
*PC | BC grading coefficient | 0.4 | |
*XP | Constant part of CJC | 0.2 | |
*MC | Collector current modulation coefficient | 0.5 | |
*XCJC | Fraction of BE capacitance under emitter | 0.1 | |
*TREF | Reference (extraction) temperature | Celsius | 25^{o}C |
*DTA | Device temperature rise above ambient in degrees C | Celsius | 0.0^{o}C |
*TAMB | Ambient (baseplate) temperature | Celsius | 25^{o}C |
*VGE | Emitter Bandgap | Voltage | 1.01V |
*VGB | Base Bandgap | Voltage | 1.18V |
*VGC | Collector Bandgap | Voltage | 1.205V |
*VGJ | EB Bandgap | Voltage | 1.1V |
*VI | Ionization voltage base dope | Voltage | 0.4V |
*NA | Maximum base dope (per cm^3) | 3e17 | |
*ER | VLF and VLR temp coefficient | 0.002 | |
*AB | Base resistance temp coefficient | 1.35 | |
*AEPI | Epilayer temp coefficient | 2.15 | |
*AEX | Extrinsic base temp coefficient | 1.0 | |
*AC | Buried layer temp coefficient | 0.4 | |
*KF | Base current 1/f noise | 2e-16 | |
*KFN | Nonideal base 1/f noise | 2e-16 | |
*AF | 1/f noise exponent | 1.0 | |
*ISS | base-substrate saturation current | Amperes | 6.0e-16A |
*IKS | Knee current of the substrate | Amperes | 0.005e-3A |
*CJS | Zero-voltage substrate capacitance | Faraday | 1.0e-12F |
*VDS | CS built-in voltage | Voltage | 0.5V |
*PS | CS grading coefficient | 0.33 | |
*VGS | Substrate Bandgap | Voltage | 1.15V |
*AS | =AC for closed buried layer; =AEPI for open buried layer. | 2.15 | |
*NFLAG | Noise flag; 1=ON, 0=OFF | 0 | |
MULT | Number of devices in parallel | 1 |
* indicates a secondary parameter
Parameter default values are those given in Philips' documentation [2] and are generally respected throughout the user community. Those defaults, however, are representative of RF or Microwave devices.
The range of many of the model parameters is restricted. In spite of extensive error-trapping in the AWR Microwave Office implementation, it is possible that some parameter errors may not be trapped. See [2] for details on such restrictions.
This model is mapped into HSPICE as a NPN G-device with parameters LEVEL and VERS set to 6 and 503, respectively. The complete set of equations is too complex to be listed here. The user should consult the references for specific information. Ref. [1] contains technical background information and theory of the model, and the documents available from Philips' web site [2] define the model in detail.
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.
Mextram is an advanced model. It should be used only where the need for accuracy justifies its complexity, and where parameter libraries are available. The Gummel-Poon model, GBJT, is recommended for simple applications.