Problem with LTSpice Simulation

Discussion in 'General Electronics Chat' started by Darent, Jan 26, 2013.

  1. Darent

    Thread Starter New Member

    Jan 26, 2013
    1
    0
    Hi everyone,
    I am quite new to LTSpice, recently I tried to simulate a voltage ref circuit. However, I got some errors like:

    Instance "m13": Length shorter than recommended for a level 1 MOSFET.

    Can you help me debug them? Thanks a lot.

    I have attached my circuit file for ur reference!
     
  2. tindel

    Active Member

    Sep 16, 2012
    568
    193
    Error: .include filename missing
    Questionable use of curly braces in ".model 2n2222_varbf npn(is=1e-14 vaf=100 bf={var} ikf=0.3 xtb=1.5 br=3 cjc=8e-12 cje=25e-12 tr=100e-9 tf=400e-12 itf=1 vtf=2 xtf=3 rb=10 rc=.3 re=.2 vceo=30 icrating=800m mfg=philips)"
    Error: undefined symbol in: "[var]"
    Questionable use of curly braces in ".model 2n3904_var1_bf npn(is=1e-14 vaf=100 bf={var1} ikf=0.4 xtb=1.5 br=4 cjc=4e-12 cje=8e-12 rb=20 rc=0.1 re=0.1 tr=250e-9 tf=350e-12 itf=1 vtf=2 xtf=3 vceo=40 icrating=200m mfg=philips)"
    Error: undefined symbol in: "[var1]"
    Questionable use of curly braces in ".model 2n3904_var2_bf npn(is=1e-14 vaf=100 bf={var2} ikf=0.4 xtb=1.5 br=4 cjc=4e-12 cje=8e-12 rb=20 rc=0.1 re=0.1 tr=250e-9 tf=350e-12 itf=1 vtf=2 xtf=3 vceo=40 icrating=200m mfg=philips)"
    Error: undefined symbol in: "[var2]"


    These are the errors that I'm getting, possibly a reorganization of the circuit will help you find your own error. It's pretty messy. I would suggest using a FET with the Body of the FET's connected to the source, as is typical of most FETs.

    What are you trying to do?
     
  3. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
    657
    Look more closely. I believe all sources and substrates are connected to +1V. I agree that this node could be simplified considerably.

    I don't see models or parameters for any of the MOSFETs. I guess there are default values.
     
    Last edited: Jan 27, 2013
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