[SI-LIST] Re: internal timestep too small in transient analysis HSPICE
- From: "Andrew Ingraham" <a.ingraham@xxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Sat, 26 Jan 2008 21:04:38 -0500
'Internal timestep too small" can happen for any number of reasons, having
nothing whatsoever to do with the .tran statement or sampling or anything
similar. There is no one fix that always works.
The internal timestep changes often throughout a simulation. When SPICE
runs into a problem, it backs up and tries again with a smaller timestep.
If this happens repeatedly, the timestep goes below some limit, and it
aborts.
One of the common causes is a semiconductor device model that has a point or
region that behaves poorly, such as a discontinuity in a function or its
derivative. This can cause problems for the simulator when it has to get
through that region. It gets stuck.
Often a "fix" doesn't actually fix the problem; it just changes something
that lets SPICE get past the problem area.
Andy
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