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Pspice simulation Help!

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ethan169

New Member
Hey Guys,

So im trying to simulate a basic Op=amp circuit in spice. Im using a spacific National semiconductor Op-amp in the LMH series. Ive downloaded the spice model and orcard drawing for the chip from National's website. Added them to a library etc and used the part in my design.

When I run the simulation I get some errors that I dont really understand. Ive posted some screen shots of whats going on below.




The errors in the schematic shown around those polarized caps is that I dont have a polarized cap that has a spice model. It shouldnt effect the simulation though. Any ideas? Ask questions if something is unclear I will try to be as clear as possible.

Thanks!
 

ethan169

New Member
Oh the top window there pops up during the simulation and is allowing me to make changes. Its "pausing" the sim and giving me these options. Then in the error log for the simulation window if you scroll all the way down it says Try tunning with .OPTION STEPGMIN
 

crutschow

Well-Known Member
Most Helpful Member
SPICE is notorious for convergence problems. So have you tried changing the .OPTION STEPGMIN value as it suggested? Sometimes reducing the accuracy requirements of the simulation will also help.

P.S. The supply filter capacitors are ignored by the simulation since it generates an ideal supply voltage.
 
Last edited:

ethan169

New Member
SPICE is notorious for convergence problems. So have you tried changing the .OPTION STEPGMIN value as it suggested? Sometimes reducing the accuracy requirements of the simulation will also help.

P.S. The supply filter capacitors are ignored by the simulation since it generates an ideal supply voltage.

I would like to try to adjust the steppgmin but was unsure of where to find this "field" I even searched in the help for this term and nothing came up?

Thanks for your response.
 

crutschow

Well-Known Member
Most Helpful Member
A Google search of Pspice stepgmin had several hits such as this and this.
 
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