Eldo MEASURE(EXTRACT) problem

Discussion in 'Cadence' started by sinan, Apr 5, 2007.

  1. sinan

    sinan Guest

    I am trying to get tplh, tphl, trise and tfall times with the commands

    ..EXTRACT TRAN LABEL=RISE TRISE(V(out))
    ..EXTRACT TRAN LABEL=FALL TFALL(V(out))
    ..EXTRACT TRAN LABEL=tplh TPDDU(V(out),V(inp))
    ..EXTRACT TRAN LABEL=tphl TPDUD(V(out),V(inp))

    inp: input net name, out: output net name

    I get RISE and FALL times correctly but I could not get tplh and tphl
    correctly,

    for example I get
    *TPHL = 2.1539N , while I should get something around 200ps ,
    (both from plot results and calculation)

    Also Eldo gives this error
    "TPLH cannot be measured . Check your input netlist
    wave1 has crossed the threshold 1 time(s) but wave2 has not (or before
    wave1).
    "
    however I see from plots both wave1 and wave2 crosses the thresholds
    I tried to increase my inputs delay, rise and fall times, did not work
    out,

    I get this error in some circuits, I am sure that EXTRACT commands are
    true, but there must be some point I am missing
    what can be the problem?
     
    sinan, Apr 5, 2007
    #1
  2. sinan

    S. Badel Guest

    I am trying to get tplh, tphl, trise and tfall times with the commands
    Don't you simply have inverted input and output in TPDDU/TPDUD ?
     
    S. Badel, Apr 5, 2007
    #2
  3. sinan

    sinan Guest


    thanks, I tried them too (e.g. TPDDU(V(inp),V(out))) and again not the
    correct result, but different results,
    when I modify as

    .EXTRACT TRAN LABEL=tplh TPDDU(V(inp),V(out))
    .EXTRACT TRAN LABEL=tphl TPDUD(V(inp),V(out))
    .EXTRACT TRAN LABEL=tplh2 TPDDU(V(out),V(inp))
    .EXTRACT TRAN LABEL=tphl2 TPDUD(V(out),V(inp))

    here results:

    TPLH cannot be measured . Check your input netlist
    wave1 has crossed the threshold 1 time(s) but wave2 has not (or before
    wave1).
    * TPHL = 2.1539N
    TPLH2 cannot be measured . Check your input netlist
    wave1 has crossed the threshold 1 time(s) but wave2 has not (or before
    wave1).
    * TPHL2 = 1.9239N
     
    sinan, Apr 5, 2007
    #3
  4. sinan

    sinan Guest


    OK I see now, I looked output waves and tried to figure out which
    combination gives 2.1539 and 1.9239 and found out that 2.1539
    TPDUD(V(inp),V(out)) is the time between

    rising input to decreasing output= 2.1539 TPDUD(V(inp),V(out)) (now it
    makes sense, U for: V(inp) , D for: V(out))
    and vice versa,

    I should have used TPDUU and TPDDD instead,

    thanks Badel again, it created an incentive to trace the error
     
    sinan, Apr 5, 2007
    #4
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