about IBIS model's ramp

Hi,
    I am a engineer of Huawei company in the city of ShenZhen in China.
    Now I am engaged in PCB signal analysis . I have met many IBIS
models .
    May I ask a question now? Thank you .
    In IBIS model, there are definition of pullup ,pulldown and other
V/I curves . Other parameters such as C_comp and PKG parameters are also

listed. So in my idea, if a driver have these V/I curves and
parameters, when a square wave is input to the driver( it has an a
standard 50 ohm load ), the output wave should be a trapeziform wave.
From this trapeziform wave , we can measure the tr and tf .
    Now I want to ask that though we can measure the tr and tf from the
output waveform, why should we define the ramp parameter in IBIS model?
Received on Tue Apr 20 23:34:08 1999