Sear,

  More information would be helpful. Usually the time step gets small
when there is a convergence issue. There are many phenomena that
may cause this type of issue, it might be best to contact your local
Cadence support.

                                                              Best Regards,

                                                                 Sheldon

Wave,

   Yes, you are correct that tweaking can help, in particular,your
example of setting cmin is good. Setting cmin is usually very effective
without greatly effecting the results. On the other hand, almost all of
the convergence issues that I have seen recently have ended up
being related to incorrectly formed models: models with large
negative resistance, non-monotonic functions(higher order derivatives
blow-up), etc.  These issues can be worked are by tweaking the
simulator parameters but it is better to identify the issue and fix it.
The bonus is that fixing the problem often significantly improves
simulation time. The down side is that typically developer's will need
access to the testcase in order to understand the issue.

                                                        Best Regards,

                                                           Sheldon