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 How to use a Newly Added Model (specify Early Voltage or Lambda for NMOS) 

Last post Sun, Nov 25 2012 4:09 AM by oldmouldy. 1 replies.
Started by Shiraz 24 Nov 2012 08:27 AM. Topic has 1 replies and 719 views
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  • Sat, Nov 24 2012 8:27 AM

    • Shiraz
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    • Joined on Sun, Sep 23 2012
    • Posts 15
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    How to use a Newly Added Model (specify Early Voltage or Lambda for NMOS) Reply

     I was trying to use an NMOS with an early voltage value specification (of 100 v to be precise). 

    I looked through the powermos.lib (powermos.olb) library and I could not find any parameters that may specify early voltage.
    I noticed that "lambda" can be used as a parameter (is this correct?): http://bwrc.eecs.berkeley.edu/classes/icbook/spice/userguide/elements.html#676

    So I went about simply plopping an NMOS device on the canvas and then right click -> edit the pspice model.

    Then I went about copying a comparable NMOS device clicking from the menu of the model editor: Model-> copy from. After copying over a model and renaming it "M2N6661WithLambda" I edited it slightlyto add a lambda value as follows:

     .model M2N6661WithLambda  NMOS(Level=3 lambda=0.01 Gamma=0 Delta=0 Eta=0 Theta=0 Kappa=0.2 Vmax=0 Xj=0
    +               Tox=2u Uo=600 Phi=.6 Kp=1.05u W=.18 L=2u Rs=20m Vto=2 Rd=0
    +               Rds=9MEG Cgso=15.45p Cgdo=8.947p Cbd=108.7p Mj=.5 Pb=.8 Fc=.5
    +               Rg=209.5 Is=10f N=1 Rb=1m)
     

    Now assuming I am doing everything right upto now , how do I use this new NMOS in my project / circuit ? I cannot see it in the parts (I tried saving the model editor and then removing and adding powermos.lib and powermos.olb all over again but this new part does not show up and it is not saved to the powermos.lib library apparently. 

    Is there a step by step tutorial online that allows someone to create and add/use such a mosfet? perhaps the easiest and simplest possible way?

    I noticed another method specified is using a generic MBreakN3 model and then just add parameters as in here : 

    http://www1bpt.bridgeport.edu/~thapa/eleg458/tut/pspice/PSPICE_MOS_TUT5.pdf

    which seems to be easier and simpler to do...

    • Post Points: 20
  • Sun, Nov 25 2012 4:09 AM

    • oldmouldy
    • Top 10 Contributor
    • Joined on Tue, Jul 15 2008
    • Woking, Surrey
    • Posts 1,444
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    Re: How to use a Newly Added Model (specify Early Voltage or Lambda for NMOS) Reply
    Things are a bit less complex than that, certainly while checking the model definition out. IF you place a part and Edit the PSpice Model from Capture, you get a new local LIB file to hold the parts that you edit the PSpice models for in the project, you edit this part in the Model Editor that opens from Edit PSpice Model and that is then the model for that part, has the original Implementation. IF you change the Model Name. ".MODEL MY_MODEL..." for the part you will need to change the Implementation property value for the Schematic part to match, you can change the Value property as well to match if you want to. IF you want to have your own library, copy the part model(s) from the schematic related LIB file and use the definitions in the Model Editor to create the LIB file, save this, then use File>Export to Capture Part Library, this will create the graphical library. In the Capture Project, use the Place>Part, Add Library to add the graphical parts and Edit the Simulation profile to add the LIB file to Configuration Files, Library.
    • Post Points: 5
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Started by Shiraz at 24 Nov 2012 08:27 AM. Topic has 1 replies.