[SI-LIST] Re: Transient sim in specific time points

Hi, Ben,

Your problem might be bigger than you think.
* If I remember correctly, HSPICE (and other flavors) solve at 
"internal" timepoints, for simulation efficiency and accuracy.  The 
.TRAN print output is then interpolated based on those internal 
timepoint solutions.
* These internal timepoints are not required to include any of the 
"breakpoints" of your input source (except time=0).
* The .OPTIONS can be used to limit the step between internal 
timepoints.  The convergence tolerance options also have an effect on 
timepoint selection, plus some of the other options.  Note that 
overconstraining tolerances can make the simulation run longer and 
perhaps make the simulation fail to converge.
* The output plot (*.tr0) probably contains the complete internal 
timepoint results.
* One possible solution: take the *.tr0 file, and write a script to 
extract the timepoints of interest.  Of course, there will be some 
tolerance needed in picking the timepoints, since they probably do not 
all fall exactly on the desired times.  One could even implement 
interpolation if needed.
* Another possible solution: make the .TRAN print time interval small; 
there might be a print step size that will hit all of your desired times 
exactly (plus a lot of others), but the file might still be smaller that 
the *.tr0 file.  Again, one could write a script to extract the 
timepoints of interest from the *.lis (*.out) file. The advantage here 
is a smaller output file (but with more overhead info). On the other 
hand, scripting might be easier with the *.tr0 file, since there is less 
text to ignore.

Best of luck.

Lynne


"IBIS training when you need it, where you need it."

Dr. Lynne Green
Green Streak Programs
http://www.greenstreakprograms.com
425-788-0412
lgreen22@xxxxxxxxxxxxxx



Ben wrote:
> Hi all
> I need to perform a transient simulation but i need the results at specific
> time instants.
>
> I know that, regardless of the internal time steps Hspice internally may
> take for numerical integration user can get the simulation results at
> specific time instants (eg. equally spaced time points) defined by .tran
> command.
>
> In my case I have a list of time points (say 1000 points) at which I need
> the transient response. These time points are not equally separated.
> According to Hspice-command-ref I guess the following statement may have a
> clue for the solution
>
> .TRAN data = dataname
> This example is a data-driven time sweep. It uses a data file
> as the sweep input. If the parameters in the data statement
> are controlling sources, then a piecewise linear specification
> must reference them.
>
>
> But I am not sure whether it can give me what i am looking for or how I can
> define "data-file" indicated as  data = dataname.
> What is the required file structure for the data-file,
>
>
> I would appreciate any input in this regard.
>   


------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
http://www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field


List technical documents are available at:
                http://www.si-list.net

List archives are viewable at:     
                http://www.freelists.org/archives/si-list
 
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu

Other related posts: