On Wed, Mar 5, 2025 at 04:27 AM, Andy I wrote:
I am uncertain what you suggested.? Why would either simulator use a "small signal linear equivalent circuit" for the transient simulation of something which is or might? be nonlinear?? Shouldn't it always solve the non-linear equations at each timestep?? That is how it is supposed to work, isn't it?
Ok yes, for transient analysis it is supposed to work that way. Therefore, at the end of transient analysis, there will be a total number of iterations done (some associated with ITS calculation and others to solve non-linear equations at successive timesteps until the end).
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Using a small-signal linear equivalent circuit makes sense only for .AC analysis.
Ok, the above is made explicit in ngspice manual's section for .AC analysis. However, in the case at hand, even .AC analysis for both simulators doesn't provide a reasonable/good result (since the calculated DC operating point isn't reasonable).
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Carlo
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Carlo