mairomaster , 01-18-2017, 04:28 AM
That is the difference in time between the two (or N) signals going down two tracks. If one of the tracks is longer, it will take the signal more time to arrive at the destination, assuming both signals have the same propagation speed. The formula is:
t = L/V
t - time of travel
L - length of the track
V - propagation speed of the signal
Propagation speed you can estimate reasonably accurately with the Saturn PCB calculator (conductor impedance tab). Once you convert the maximum propagation delay required to a distance (length) tolerance, that will help you to length match the signal tracks. Length matching is a very common topic - you can read a lot about it here on the forum and on the web in general.
If your examples are real, 50ps for uart sounds ridiculously small to me.