Simple PSPICE netlist - all nodes floating?, Pspice netlist, however simple, not work

I have been getting back into Pspice, so I donwnloaded the evaluation version, and tried to simulate in the time domain, a very simple circuit with a Miller capacitor. I wanted to see how the slew rate depended on the Miller effect.

But when I try to run the simulation, I get a bunch of error messages. Here is the netlist:

And here are the errors:

Thanks for your help!


(and BTW, this is the first post on this website ever - if I did something wrong posting-wise, cut me some slack, please)

It's been a while since I've manually entered spice stuff (and I've
never used PSPICE), but I think you need to define a voltage
source for your +5V.

Thanks, I believe that's it - I'll check when I get home today.

Thing is, I used the PSPICE capture tool to create the netlist, I didn't write it down manually. So I thought if I use the power symbol, PSPICE will take care of that actually, you know, being VCC. This PSPICE package is confusing, it seems to have two different ways of creating schematics. One is this I used, and is branded "OrCad", the other seems to be the original PSPICE one, but that's not integrated into the project - when you start a "project", you get to use the OrCad schem capture tool.

This stuff shouldn't be this confusing. I should be able to concentrate on the design, not the tool.

This post has been edited by blindbiker on October 30, 2007 09:08 am

Well, I tried what you said. Apparently, that previous type of source doesn't have a single property - not even voltage??! So, I switched to another power component (you will see in the schematic). But that didn't do the trick:

Don't know what to say. I entered the same schematic
in LTspice , this is the exported netlist:

Only notable differences I see is that GND is named "0" here.
It seems PSPICE doesn't like your GND. I'm sure the program
includes examples that you can compare to yours; you could
also check out the documentation, might find something there.

Only notable differences I see is that GND is named "0" here.
It seems PSPICE doesn't like your GND. I'm sure the program
includes examples that you can compare to yours; you could
also check out the documentation, might find something there.

I entered the same schematic in PSPICE's "Schematic", instead of going the project-route. The "Schematics" program seems to be a separate schematics capture, different from the one named "Capture" (which does exactly the same thing but looks different and was developed by OrCad), and "Capture" is integrated in the whole project creation process, whereas "Schematic" isn't. Or at least, it doesn't seem to be.

But regardless of that, you can still make analyses, and analyze I did. Because "Schematic" accepted my netlist without reproach.

I love it when huge software packages are actually not even understood by their makers - this stuff has gotten so out of hand that nobody in the world knows anymore how these humongous packages really work and what they can do.

Anyway, rant off. Main thing is, I managed to enter my schematic (exactly the same way as I did in OrCad's "Capture") and there were no errors in the netlist, did my time-domain things and am almost happy. Of course, the actual circuit I am testing is much more complex than the 4-node NMOS stage.

LTspice? I'm going to try it right away.

This post has been edited by blindbiker on October 31, 2007 01:52 am

Tried LTspice. While just a little bit underpowered, it's very clear, very straightforward. There's nothing in there that I'd would wonder "how did this module end up in here, and what does it do?" So, it's going to be my Spice software for the time being, at least while I'm working from home.


Thanks for the eccellent hint!

I was having a similar error. I had to change the name of my ground (GND) to "0". Once I did that, all of my floating nodes, and my floating "GND" were taken care of. Kind of makes you wonder why the programmer didn't just make it set to 0 in the first place.... circuit won't work if you don't re-name the ground to 0.

SPICE defaults to '0' for ground. Some packages use GND for some reason; those that do *should* have an option to use 'GND' as the common node.

In a pinch, one could chuck in a "RGND 0 GND 1u" into the netlist to more-or-less short them together.

Tim

Yet another blast from the past...