When I am using APS for PSS (shooting Method) using swap file, APS is being disbled.
How can prevent APS being disabled.
Unfortunately this option is not well documented yet - there's a CCR to get that fixed. It's described in "spectre -h options" as:
112 dc_pivot_check=no During DC analysis numeric pivoting is only performed when bad pivot is detected. Possible values are no and yes.
You can enter this by going to Simulation->Options->Analog and then at the bottom of the form (or the Misc tab in IC61X) in the Additional Parameters field, enter "dc_pivot_check=yes".
I'm not sure it's that important though... it might speed up the convergence during the DC analysis though.