#791 AC simulation fails in standalone Ngspice but works in KiCad's internal simulator

[li meilin]

I'm using KiCad 9.0 to design a circuit and simulate it via the internal simulator. The simulation runs successfully in KiCad, but when I try to run the exact same netlist in standalone Ngspice (LTPS build), it fails during AC analysis.

• KiCad Version: 9.0
• Ngspice Version: 44

• Simulation type: AC analysis

• The same netlist simulates successfully inside KiCad.

• The model files are correctly loaded (as verified by KiCad).

• This might suggest a discrepancy in model parsing or solver configuration.

• Use the attached netlist (variant_62.cir) and run it in Ngspice.

• Observe that Ngspice fails with singular matrix and timestep errors.
• Run the same in KiCad's simulator — it works fine.

Attachments：

• Full netlist
• Log files from Ngspice
• Screenshots showing kicad simulation results