bad rise time in eye diagram link to data speed

Thread Starter

yef smith

Joined Aug 2, 2020
186
Hello,In the eye diagram bellow the top Wall distortion is caused by transmition line induction voltage drop.
the side wall low slope (big rise time)could be caused by high data rate .
why high data rate causes the slope to decrease thus getting high rise time?
what is the speed and its effect on the slope. why if we have higher speed then the slope gets worse. my logic says that the slope cannot change at all. if we put higher speed then our output capacitance will charge to less value thus creating the upper wall. But i cant see the effect on the slope
Thanks.

1615378038774.png
 
Last edited:

MrChips

Joined Oct 2, 2009
23,073
Are you certain that the rise time is increasing (slope is decreasing)?
At higher data rates you have to increase the horizontal sweep rate on the oscillosope in order to view the trace properly. This might be fooling you into thinking that the slope is decreasing.
 

Thread Starter

yef smith

Joined Aug 2, 2020
186
Hello Mr.Chips also we can see the rise and fall acts by exponent with RC coefficient,but the is an inductance also in the transmission line so there could be overshoot behavior.
How can i show the full equation for transmission line?
that give exponential rise with overshoot?
Thanks.
 
Top