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May 19th, 2019, 8:34pm
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Self inductance Versus Loop Inductance of a trace (Read 904 times)
curious
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Self inductance Versus Loop Inductance of a trace
Nov 25th, 2017, 11:49pm
 
Hi ,

I am trying to find information on what is the difference between loop inductance of a trace versus self inductance of a trace. Can you please clarify?  I am trying to learn how these inductance of traces would affect the high speed signal paths and what challenges one have at the PCB level.

Thank you
Curious
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Maks
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Re: Self inductance Versus Loop Inductance of a trace
Reply #1 - Nov 26th, 2017, 8:31am
 
Usually, a term "loop inductance" is used to describe a system that contains both signal and its return path - as opposed to "partial inductance", that describes magnetic field interaction between two current elements (that may or may not belong to the same "trace" or "loop").

As a simple example - a straight metal line may have large (self) inductance, but if its return path is another metal line running in parallel and close to the first one (so that the area of the loop is small), the current in second wire will "cancel" the effect of the current in the first wire, so that the loop inductance of this system (which is the same as a self-inductance of this system) is small.

Regarding the second question - very generally - inductance in high-speed signal path may lead to extra delay, signal overshoot, oscillations, ground bounce, and other kinds of (usually) detrimental effects.
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curious
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Re: Self inductance Versus Loop Inductance of a trace
Reply #2 - Dec 10th, 2017, 7:08pm
 
Thank you!
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