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XSpice simulation of an Op Amp with a Negative Rail.

jimmallabar

I'm having trouble running XSPICE simulation with an op amp that uses -14V for VEE.  I've tried using a VSRC2 set to -14V, but the pin on the op amp reported +14V when I plotted it.  Likewise, I've also used a VSRC set to +14, but the + side of the VSRC tied to GND and the - side tied to VEE.  same result. 

 

Does anybody out there attempt to use the simulation feature of CircuitStudio?

 

Thanks,

 

Jim

  • 0

    More information on this subject.  The issue is not necessarily that the negative supply is not the right value.  One of the problems is that when running a new XSpice simulation from CircuitStudio the old results do not get deleted or overwritten.  At the bottom of my message window, after it says "Finished Output Generation", are 2 error messages.

    [Error]

    Simulation

    XSpice

    Error: Unknown variable gain\xiq

    8:36:25 AM

    11/29/2017

    28

    [Error]

    Simulation

    XSpice

    Error: Cannot evaluate device equation for g1\xiq-\xu1

    8:36:25 AM

    11/29/2017

    29

    The two errors at the end point to this model in the netlist  file:

     

    .subckt VCCS_LIM_IQ VC+ VC- IOUT+ IOUT-

    .param Gain = 0.001

    *.param Gain = 1e-3

    G1 IOUT+ IOUT- VALUE={IF( (V(VC+,VC-)<=0),0,Gain*V(VC+,VC-) )}

    .ENDS VCCS_LIM_IQ

    This subcircuit is called by the top level OPA170 subcircuit twice:

    XIQ+ VIMON MID VCC MID VCCS_LIM_IQ

    XIQ- MID VIMON VEE MID VCCS_LIM_IQ

     

     

    My XSpice skills are very rusty, I suspect there is some sort of issue with the syntax here.

    Any suggestions?