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I am having some problem with one of the boards I am working on, the noise from the inductor is coupling to an analog circuit and I was wondering if there are inductors that has a ground shield. I have seen several research papers but no products.

Also, is there a good way to deal with this type of noise issues from inductors other than shielding? I am looking for general direction.

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Try a toroidal inductor? –  Matt Young Feb 6 at 2:42
    
Which noise from an inductor? I can think of more than a couple mechanisms by which a circuit with an inductor might be "noisy". –  Phil Frost Feb 6 at 3:14
    
@PhilFrost Essentially, if I cover the inductor with a copper tape and ground this tape, the noise goes away, so I am assuming it is not common mode and my sensitive analog is picking up the noise. analog circuit is an amplifier that has a lot of amplification (6M times) and I see the additional noise at the output due to this. –  Ktc Feb 6 at 3:52
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1 Answer 1

up vote 6 down vote accepted

Magnetically shielded inductors are common. Ones with a core shaped like a spool from sewing thread have an open magnetic circuit and they therefore have more leakage inductance and can couple to conductors outside. Things like pot cores and toroids are better.

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Electrostatically shielded inductors are not very common. You have to be careful not to create a shorted turn that would couple with leakage inductance. Electrostatic shields (and double shields) internally between windings of a transformer, for example, are relatively common.

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Sometimes you will see a copper band on the outside of a transformer-- that is actually magnetic shielding (called a flux band).

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Could you point me out to an example of a magnetically shielded inductor? –  Ktc Feb 6 at 2:52
    
See my answer above. –  Spehro Pefhany Feb 6 at 2:56
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