When you do not have a feedback for a high gain amplifier, it is not possible to avoid saturation in the output. You need to have a DC feedback at least and then you can find the gain.
In reply to HamidKhatibi:
Thanks for reply,
However I am facing a very strange problem in my simulation, please help me with this:
I am running a parametric simulation to experiment & get the optimal bias current of Op-Amp .
For this I gave a list of "I_bias" as "5u 7u " in the parametric analysis window, and ran a parametric transient analysis with these 2 parameters
Problem is the output I get with 7u in above parametric analysis is very different from the same value plugged directly in transient analysis.
I figured out that if I remove 5u in the list of current values I pass in parametric analysis then the output of parametric analysis and transient analysis become same.
I have never seen this difference before, is this related to some initial value problem ? [part of 5u solution getting used for 7u simulation ?]. Please help me in debugging this.
Update: I figured out that if I do skipdc transient analysis, my results are okay as expected, what does that imply, the circuit's DC behaviour is not good ? And also skipdc takes much longer, what should be the most appropriate initial condition and how may I include them ?
Thanks a lot.
In reply to OneNewBoy:
Using skipdc is not a good idea - it means that the transient will have a much harder time converging.
The behaviour you are seeing suggests that your circuit has more than one stable operating point.
In reply to Andrew Beckett: