[SI-LIST] IBIS MODEL QUESTION

 Hi, eveyone;

I have encountered some ibis model problems recently, these problems happend
quiet a lot, here are some examples errors below;..


ERROR - Model prbcbu: The [Rising Waveform] 
      with [R_fixture]=50 Ohms and [V_fixture]=0V
      has TYP column DC endpoints of  0.00V and  0.68v, but
      an equivalent load applied to the model's I-V tables yields
      different voltages ( 0.01V and  0.77V),
      a difference of 100.00% and 11.76%, respectively.
ERROR - Model prbcbu: The [Falling Waveform] 
      with [R_fixture]=50 Ohms and [V_fixture]=3.3V
      has TYP column DC endpoints of  2.64V and  3.30v, but
      an equivalent load applied to the model's I-V tables yields
      different voltages ( 2.56V and  3.30V),
      a difference of  3.27% and  0.00%, respectively.

 I just wonder how does ibis checker to find these error?? and it's OK if I
ignore these message?? can I fix it by myself??

there's another case is that  usually in the simulated  waveform the Vmeas
falls between Vih and Vil, and then I can use it to measure the flight time
and buffer delay  , but what if Vmeas is higher than Vih??I can't find a
reference point to do the dealy measrement! so dose this ibis model has
wrong number for Vmeas ( let's asy 3.3V) or I should use another approach
in my tool?? 

 thanks





 




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