#323 Discrepency between Ngspice and Xyce simulation Issue created by adrienluitot Environment OS: Ubuntu 24.04 Tools: Qucs 24.4.1 Simulator: Ngspice-44 and Xyce 7.8 Expected Behavior Having similar simulation results between Xyce and Ngspice. Actual Behavior We are designing a simple LNA at 2.45GHz. Here is its schematic and some ngspice simulation results: lna_and_ngspice On the right we see the Re(Z11) is 47.047Ω (with Ngspice). When I run the same design, with the same parameters/variables, and the same simulation, but with Xyce, I get these results: results_xyce The discrepancy is not negligible here, mostly for Re(Z11), almost 10% difference. For other results, there is not such a discrepancy, for instance, gain is pretty similar: 15.531dB for Ngspice and 15.561dB for Xyce. I don't know if the error comes from: • Me (Xyce installation maybe ?) • Ideal components (maybe Xyce and Ngspice treat R,L,C slightly differently -> I will soon try with IHP's real components) • Discrepancy between IHP's Ngspice and Xyce models • Something else Steps to Reproduce the Problem 1. Create a schematic in Qucs 2. Simulate with Ngspice 3. Copy whole schematic (design, parameters, simulations) 4. Adapt to Xyce (include & plugin) 5. Simulate with Xyce IHP-GmbH/IHP-Open-PDK