LTSpice MOSFET model

Discussion in 'Homework Help' started by domino89, Apr 28, 2014.

  1. domino89

    Thread Starter New Member

    Sep 24, 2013
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    I have this kind of MOSFET model:
    *************************************************
    .model nmos. NMOS
    + LEVEL=1
    + LMIN=0.5e-6 LMAX=50e-6 WMIN=0.9e-6 WMAX=1
    + VTO=0.7 GAMMA=0.45 PHI=0.9
    + NSUB=9e14 LD=0.08e-6 UO=350 LAMBDA=0.1
    + TOX=9e-9 PB=0.9 CJ=0.56e-3 CJSW=0.35e-11
    + MJ=0.45 MJSW=0.2 CGDO=0.4e-9 JS=1.0e-8
    .model pmos. PMOS
    + LEVEL=1
    + LMIN=0.5e-6 LMAX=50e-6 WMIN=0.9e-6 WMAX=1
    + VTO=-0.8 GAMMA=0.4 PHI=0.8
    + NSUB=5e14 LD=0.09e-6 UO=100 LAMBDA=0.2
    + TOX=9e-9 PB=0.9 CJ=0.94e-3 CJSW=0.32e-11
    + MJ=0.5 MJSW=0.3 CGDO=0.3e-9 JS=0.5e-8
    *************************************************
    And i want to use it in LTspice but it doesnt work... Do i need to edit it?
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,791
    1,103
    Yes. Paste the text onto your schematic as a spice Directive, then correct 'nmos. NMOS' and 'pmos. PMOS' to 'nmos NMOS' and 'pmos PMOS' respectively.
     
  3. domino89

    Thread Starter New Member

    Sep 24, 2013
    22
    0
    I just did it... Same as before. But arent 'nmos.' and 'pmos.' just the transistor model names? So changing it to: without a dot wont change anything? Or this model just doesn't work... I was tasting it on simple inverter and i got output signal same as input.
     
  4. crutschow

    Expert

    Mar 14, 2008
    13,001
    3,229
    My LTspice MOS library (LTC\LTspiceIV\lib\cmp\standard.mos) has the models in this form for nchannel and pchannel devices:

    .model Si7386DP VDMOS(Rg=1.7 Vto=2.57 Rd=3.5m Rs=1.4m Kp=58 Lambda=.014 Cgdmax=.67n Cgdmin=.1n Cgs=1.56n Cjo=1.56n Rb=6m Is=2.3p N=1.075 tt=25n mfg=Siliconix Vds=30 Ron=7m Qg=11.5n)
    .model Si7409DN VDMOS(pchan Rg=3 Vto=-0.8 Rd=7.6m Rs=5.7m Rb=10m Kp=72 Cgdmax=1n Cgdmin=.25n Cgs=1.7n Cjo=.5n Is=50p mfg=Siliconix Vds=-30 Ron=19m Qg=25n)


    so you might try modifying your model to correspond. Note that the pchannel device have "pchan" as the first word in parenthesis but the nchannel device has no indicator (apparently nchannel is assumed if "pchan" is not there).
     
    Last edited: Apr 28, 2014
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    It works just fine for me.
     
  6. domino89

    Thread Starter New Member

    Sep 24, 2013
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    Wierd... What could i make wrong if its working for u :/
     
  7. crutschow

    Expert

    Mar 14, 2008
    13,001
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    I'd look for a typo.
     
  8. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Are you sure you have the model text as a Directive (a 'dot command'); not a Comment ?
     
  9. domino89

    Thread Starter New Member

    Sep 24, 2013
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    It works ! My mistake was that I wasnt declaring transistor sizeing...
     
  10. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Good that it works for you. I didn't need to declare transistor size though.
     
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