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Subject: Hspice Co-simulation Error
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YSShin
Posts: 8
Online: User is Offline
3/07/2006 5:14 PM  

Hello, All.

I've tried to run Allegro PCB SI 15.5.1 with Hspice 2004.03.
At first, it seems to work very well, but the job is aborted in a few minute.
In the file of waveforms.lis in the "sim" directory,
I can find following error message.

 **error**  internal timestep too small in transient analysis

          time =  6.29875D-09;  delta =  1.19326E-20;  numnit =   535

Even I give a transition condition as follows,

.tran 0.010000ns 20.000000ns

It is changed.

If you have any experience about this issue or any advice,
Please let me know.

Thanks in advance.
Best Regards,
YS Shin
lwang
Posts: 0
Online: User is Offline
3/08/2006 11:22 AM  
This is most likely a HSpice issue. I met this issue before when I simulate s-parameter models in HSpice. You could try increase the stimulus frequency or Try to use 2005 version of HSpice.
Kalevi2
Moderator
Posts: 69
Online: User is Offline
3/08/2006 1:38 PM  
Yes, this is a very common HSPICE error because it cannot find a time step small enough to give the same solution at some point in the future. You have elements in your circuit that make it unstable. Check the synopsys site for more details. I find connector models often get this error when unused nodes are not properly terminated or grounds are not properly connected. Sometimes it is only 1 node that you need to connect properly.
Kai Keskinen
YSShin
Posts: 8
Online: User is Offline
3/08/2006 2:50 PM  
Thanks for your reply.
In my case, it seems to me that is dependant the slew rate of stimulus.
And I couldn't find the part of root cause,
But it has defferent channel, then it runs.

Finally, I want to confirm, it can settle down if I use Hspice2005.

Best Regards,
YS Shin
riddoch
Posts: 8
Online: User is Offline
3/23/2006 8:04 AM  
I have had a similar error in the past, one thing that helped was the use of the HSPICE option RUNLVL. I am using 2005.9 so I don't know if it will work with 2004.
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