simon2 wrote on Sep 23rd, 2007, 3:15am:Hi Geoffrey,
this response is probably too late to help you, so I am posting for the benefit of other latecomers ....
It was savithru who was having trouble ...
Quote: If you intend to become an analogue designer as a career, I suggest you get hspice - you will find that it is much easier to access these features and can do so with a line or two of text in your scripts. The downside is, hspice's convergence is not quite as stable on large circuits so requires such intervention more often than spectre, however on circuits that converge in neither simulator, hspice is easier to sort out.
Spectre has a command-line interface as well; don't know what your comment is really trying to say.
Quote:Convergence is a large and complex topic but as an experienced spicer, I can make a few general comments that might help:
- Homotopy based simulators seem more stable than others
- Gear method seems better at DC convergence than others, however occasionally
Gear is an integration method for transient analysis -- what does this have to do with dc convergence? I don't think the transient integration method is used for the pseudo-transient.
Quote:- Often a circuit will converge for tran but not DC, so consider using only tran in your design flow (be prepared to do a lot of post simulation processing).
If it can converge for tran, then you should be able to generate a nodeset for running dc. Unless your simulator doesn't actually find the time=0 solution (I've heard some of the fast spice simulators don't, they just start running and hope that the problems resolve themselves during the transient).