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February 25, 2011


George Storm

I prefer analytic solutions when they apply - as they do for these circuits.

This will work when you can't find an analytic solution. But for the same number of iterations the trapezoidal solution (as used by default in SPICE) is more accurate - and the algorithms will give you your specified accuracy more-or-less automatically.

However, you do need to use proper SPICE syntax; SPICE allows you to specify different behaviours for different types of simulation, and "AC" is the syntax that is used for small-signal ("AC") analysis. What you need to specify for this is a sinusoid.
If you want to fix the simulation times you can do that too - set the option RELTOL to 1, and control the simulation via the minimum time step.

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