The Designer's Guide Community
Forum
Welcome, Guest. Please Login or Register. Please follow the Forum guidelines.
May 20th, 2024, 7:37pm
Pages: 1
Send Topic Print
Spectre convergence problem near END of a simulation (Read 426 times)
wave
Senior Member
****
Offline



Posts: 117
Silicon Valley
Spectre convergence problem near END of a simulation
Mar 23rd, 2012, 4:47pm
 
Hello all - I'm using Spectre to run transients on a relaxation oscillator.
Using some normal oscillator tricks (Trapezoidal, InitCond), it starts to oscillate correctly.  
Then near the END of the Trans simulation I get all sorts of warnings; the usual list of things blowing up, Rel tolerances, try this, try that.
ex:  Failed test: | Value | > RelTol*Ref + Abstol

...update too large: ....

If I change the Trans sim time and/or accuracy (conserve/moderate/liberal) it does not change.
Trying Analog options now, but that's not helping much either.

This is steady state, so nothing SHOULD be changing drastically.
This is preventing me from running iterative corner sim loops.

Ideas?

thanks,
Wave
Back to top
 
 
View Profile   IP Logged
ywguo
Community Fellow
*****
Offline



Posts: 943
Shanghai, PRC
Re: Spectre convergence problem near END of a simulation
Reply #1 - Mar 29th, 2012, 6:40pm
 
Hi wave,

There are many possible reasons. Probably the model is bad, any inductor inside your circuit, the simulator options ....

Please check the following.
  • Is there anything wrong in the circuit topology?
  • Does the oscillator operate steadily before it has the unconvergence problem?
  • Is there any step in supply?
  • Is there any inductor?
  • Do you set max time step? If NO, please set a reasonable value.
  • Switch to gear2only if the oscillator can start up with gear2only.


Best Regards,
Yawei
Back to top
 
 
View Profile   IP Logged
Pages: 1
Send Topic Print
Copyright 2002-2024 Designer’s Guide Consulting, Inc. Designer’s Guide® is a registered trademark of Designer’s Guide Consulting, Inc. All rights reserved. Send comments or questions to editor@designers-guide.org. Consider submitting a paper or model.