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	22 Jul 2014 06:52:59 -0700 (PDT)
Date:	Tue, 22 Jul 2014 09:52:59 -0400
Message-ID:	<CAOuGh89=mQ01sbs+Ugc3sEPUNWGexEpR_VJANTg2W_3DStUzQQ@mail.gmail.com>
Subject:	[geda-user] Do you put ground planes under inductors?
From:	Bob Paddock <graceindustries AT gmail DOT com>
To:	geda-user AT delorie DOT com
Reply-To:	geda-user AT delorie DOT com

 Filippo's question about inductor footprints raised a question in my
mind about inductor layout placement.

I've read conflicting design advice on if a ground plane should be
placed under the inductor used in switching power supplies.

One school of though says the ground plane acts as a shield, doesn't
put slots into the plane to interfere with return currents etc., this
seems to be the most common approach.  This seems to assume everything
is perfect in the real world.

The other school of thought is not to put the plane under the inductor
because the magnetic flux could introduce currents into the ground
plane modulating 'ground', a type of ground pulling.  This seems to
assume the real world is not perfect, ie. there are real world effects
that we don't really want.

Comments?

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