No ground in the circuit
The simulator needs a voltage reference before it can solve anything. Add a ground to every isolated analog section.
Britt Espinosa
Last Update 15 days ago
Every analog circuit needs one node the simulator can call zero volts. Without it there is no reference to measure anything against, and the run stops before it produces a single number.
The messages you may see
Before the run starts:
A ground is required for proper simulation. Add a ground component before running simulation.
In the Status tab of the Info panel, under the title Missing ground reference:
One or more circuit sections are missing a Ground reference.
If you open the technical details, the underlying engine text often mentions a singular matrix, a floating node, or no DC path to ground. All of those point at the same thing.
Add a ground
- Press G, or pick the ground from the Components panel.
- Place it on the return side of your supply, usually the negative terminal of the source.
- Wire it in so the terminal is connected rather than sitting next to the wire.
- Run the simulation again.
Grounds do not count toward the component limit on your plan, so adding one never pushes you over a cap.
One ground is not always enough
The message says sections for a reason. A circuit can contain several islands that share no conductive path, and each of those needs its own reference. The product's own steps are:
- Connect one node in each isolated analog section to Ground.
- For an intentionally isolated transformer secondary, connect a very large resistor such as 1 GΩ from that section to Ground.
- Run the simulation again.
The second step is the one people miss. A transformer secondary, an optocoupler output, or a capacitively coupled stage is isolated by design, and a 1 GΩ resistor to ground gives the solver a reference without changing the behavior you care about.
Check that the ground is wired in
A ground symbol dropped near a wire looks connected on screen and carries no current. Click it and confirm its pin sits on the wire endpoint. If the circuit reports the same problem after you added a ground, this is usually why.
Net labels are the other trap. A ground reached only through a net label that appears once in the schematic connects nothing, and the schematic status list flags it with a warning about a net label placed once.
If the message keeps coming back
Turn on the Info panel and read the Status tab. Use Show in schematic on the issue to select the part that raised it, then follow the wire back toward your supply. If the schematic looks correct and the message persists, use the copy action on the issue to grab the technical details and its support code, and send those to support along with the circuit name.