Hi all,

I just got a very annoying problem in tran analysis. Basically, I was doing simulation on my amplifier. First i tried to run transient analysis for 1us and the result seemed reasonable. Then I reduced the simulation time to 200ns just to take a close look at the waveform, and the result shows that the amplifier starts to oscillate.  After playing around with the spectre for a while, I noticed that the only difference between these two simulation setup is the step size, 1ns for the 1us ananlysis and 200ps for the latter. So I arbitarily set the step size to 200ps and run it for 1us. This time the amplifier begins to oscillate as well. Now, I am wondering why the difference in step size could cause such a begin difference in tran response and how should I set the step size in order to do things right. Anyone having this experience before please give me a hint. thanks in advance.

Mike