Decreasing the step size changes output

[bkim334]

For some reason, in the attaches circuit, when I run a transient analysis using a TMax of  1e-005, the output is what I should be getting; however, if I change tmax to be 1e-6, the output peaks at very low times to a value of around 1e294. When normally run, my maximum value is less than 600mV. I was just curious if anyone knew why changing tmax messes up my output and whether or not there is a setting I could change to fix this. I need my output to look around the same as in the current circuit, but with a width of less than 100ns, so a tmax of 1e-5 will not be sufficient. Thank you!

[andmboa7 · Accepted solution]

Hello bkim334!

Look you are running a transient analysis but you are using a AC source, which means it would have time-dependent values!

Multisim computes the circuit’s response as a function of time. This analysis divides the time into segments and calculates the voltage and current levels for each given interval

So definitely it would affect the response when you change Tmax

[bkim334]

Ahh that makes sense. So I should be running an AC analysis, right? 

[andmboa7]

Hey! bkim334

Take into account that Transient Analysis is base on voltage vs time

AC analysis would be gain versus frequency and phase versus frequency.

It would depend on what you are trying to analyze.... the thing is that you cannot expect the same output or outcome to the analysis to be the same if you change the Tmax