signals interference

[karimoviç]

What's the phenomenon of signal interfernce ??
how to eliminate the phenomenon of signal interference?
robertferanec

[robertferanec]

Hello karimoviç I am not sure what you mean. Could you be more specific?

[karimoviç]

okey , why sometimes we should use wire with equal length , (create a net classe , rules , length matching ..) what's the aim of using the same length ??

[chitransh92]

Hi,
All this is done to improve the signal integrity of you design.

if you want a gist what "Signal Integrity" means, Just google it.
If you want a better understanding on Why, How, Where it occurs and all its other details refer to "Signal Integrity : Simplified" book by Dr.Eric Bogatin.

If you want further more, Refer some good books on Electromagnetic theory. 🙂
The last option may be overwhelming.. 🙃


Thanks.

[robertferanec]

I will just add.

Why length matching? Signals travel at some speed - longer the distance is, longer the signal will travel. The thing is, when we work with very high speed interfaces, we would like all the signals to arrive at the same (or at very similar) time. So we would like all the signals from CPU arrive at the same time to the memory chip. And one of the ways to achieve this is to be sure, that all the signals travel the same distance, so they arrive at the same time.

However, this is a very simple explanation, because there are many factors what influence the time when signal will arrive. Length is only one of the factors, but it is good enough if some other conditions are met (e.g. if signals are routed on the same layers etc)