[SI-LIST] Indcutance role in EMI

Hi all,

I have doubt regarding inductor functionality in power supplies and
reducing EMI.

 

1.      We use common mode choke or ferrite bead to reduce the high
frequency noise in the circuits
2.      But the when inductance present in the ground or at the IC pins
( lead inductance) it will cause ground bounce or induced voltage due to
the flow of noise current. 

 

In the first case we can assume that inductor will act as open circuit
or very high impendance for the high frequecy noise , so it is nopt
allowing the high frequency noise.

 

In the second case the noise current will flow through the inductance,
due to the change in the current, V=di/dt  voltage get induced, this
will result in ground bounce.

 

My questions are: is my view correct in the both cases or not. If it is
correct, why the inductor is behaving differently for the high frequency
noise in the two cases.

 

 

 

 

Thanks& Regards 

U.K.UMAMAHESWAR

 



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