Speeding up temperature dc-sweep.

Discussion in 'Cadence' started by Svenn Are Bjerkem, Oct 30, 2006.

  1. Hi,
    When a circuit take long time to find its dc-point, it is recomended to
    use the write=spectre.dc and then readns=spectre.dc as a "seed" to find
    the dc-point. This also normally speed up the finding of the operation
    point.

    Now I am doing a dc-simulation with a temperature sweep. I cannot see
    any difference in simulation speed if I use the readns=spectre.dc or
    not. From the timestamp of the spectre.dc file, I see that it is
    written once at the start of the simulation, then no more. This lead me
    to suspect that it is also only read once during startup, and then no
    more, hence it is not possible to speed up a dc-sweep this way. I know
    that the circuit has some problems with convergence, and thus really
    expected a speed up.

    Any idea?
     
    Svenn Are Bjerkem, Oct 30, 2006
    #1
  2. Hi Svenn,

    If you're doing the sweep of temperature as the dc sweep, then each point
    will start from the previous solution point anyway. readns will only help with
    the first.

    From spectre -h dc:

    16 write File to which solution at first step in sweep is
    written.
    17 writefinal File to which solution at last step in sweep is
    written.


    If you were doing a parametric sweep of dc analyses, then readns/write would
    help, but would be slower than doing a dc sweep directly.

    Regards,

    Andrew.
     
    Andrew Beckett, Oct 31, 2006
    #2
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