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 UltraSim DC Fail 

Last post Thu, Apr 9 2009 6:26 AM by EricCDN. 1 replies.
Started by OzgurAtes 30 Mar 2009 12:04 AM. Topic has 1 replies and 1444 views
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  • Mon, Mar 30 2009 12:04 AM

    • OzgurAtes
    • Not Ranked
    • Joined on Mon, Jul 28 2008
    • Posts 1
    • Points 20
    UltraSim DC Fail Reply

     I am simulating a parasitic capacitance extracted toplevel circuit with UltraSim 6.0. I have a problem of DC operating point calculation. UltraSim says in output log that "DC simulation finishes without reaching steady state" at the beginning of transient simulation. Then all bias voltages begin to make their settling behavior to their final value, but it takes a lot of transient simulation time. Is there a method at UltraSim to calculate steady state operating point at the beginning of transient simulation correctly?

     

    Thanks in advance,

    Ozgur 

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    • Post Points: 20
  • Thu, Apr 9 2009 6:26 AM

    • EricCDN
    • Not Ranked
    • Joined on Fri, Aug 29 2008
    • Columbia, MD
    • Posts 15
    • Points 425
    Re: UltraSim DC Fail Reply

    You can try .usim_opt dc_prolong=1 which will extend the dc calculation until a stable operating point is reached.

    See cdsnhelp Chapter 3 of UltraSim User Guide for more dc options and details.

     

    • Post Points: 5
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Started by OzgurAtes at 30 Mar 2009 12:04 AM. Topic has 1 replies.