ac analysis vs transient analysis
Well, I try a short explanation:
1.) In dc analysis a voltage or a current or a global parameter (resistor, temperature) is swept - and the resulting voltage resp. current distribution in the nezwork is computet. Important: During this analysis all ac relevant parts (capacitor, inductor) are set to ZERO. This analysis is important for producing characteristic transfer curves like Ic=f(Vbe).
2.) During TRAN analysis first an initial operating point is calculated (based on dc values) and after that all momentary voltages and currents are computed as the result of a time dependent voltage or current source - including, of course, the influence of capacitors and inductors as well as all non-linearities (clipping effects due to voltage limits etc.)
3.) AC-analysis does NOT take into consideration any non-linearities. Based on the actual bias point the small signal behaviour is analyzed (using the slope of characteristic functions). Therefore, the input signal may be as large as you want (best choice: 1 volt or 1 amp).
I hope this helpes and I didn´t forget some important points.
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