I'm trying to set up a project simulation in Altium Designer. I have some circuits across two sheets:

First Sheet

Second Sheet

As you can see, I included a separate analog and digital ground. I connected them in order to perform a simulation of the circuit using the Mixed Simulation Toolbox.

Whenever I try to start the simulation i get this message:

Error message

What am I doing wrong? The GND node is in the schematic (both schematics actually) and all the components have models.

The voltage generators are simulation-only components.

I manually created some SUBCKT models for the connectors that have no internal connections.

Thank you for any help.

  • \$\begingroup\$ Try making all of your grounds 'SGND'. \$\endgroup\$ Apr 25, 2022 at 13:38
  • \$\begingroup\$ @ChrisKnudsen I'd like to keep the analog and digital grounds separate. The two nets should however be connected (see schematic). The GND node is connected to those nodes as well. \$\endgroup\$ Apr 25, 2022 at 13:47
  • 1
    \$\begingroup\$ You're working with a persnickety simulator. You'll likely have to do things "its" way. If you're still having trouble, or would like to voice your displeasure with your multi-kilobucks-software, then try the official Altium forum. Lots of good people there. \$\endgroup\$ Apr 26, 2022 at 12:33
  • \$\begingroup\$ @ChrisKnudsen Ahahaha, alright thanks, I will go voice my displeasure there. Luckily as a student I don't pay a single kilobuck. \$\endgroup\$ Apr 26, 2022 at 18:26

1 Answer 1


The best solution is to use a single ground - this is true for real circuits as well. Multiple grounds will tend to cause more harm than good. But, getting back to Altium. Use a single ground or try placing a net label called 0 (on the wire tying the two grounds together). This is what the SPICE simulator is looking for. If that isn't working then stick a 1m (milliohm) resistor between the two grounds.


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