Re: PCB Layout...loop areas?

Terry Given wrote:
> bill.sloman@xxxxxxxx wrote:
> > bigschlong@xxxxxxxxx wrote:
> >
> >>Hi!
> >>
> >>I've been reading some PCB layout design documens. When they say loop
> >>areas, are they only referring to loops on one side of the PCB?
> >>
> >>I looked at my design and noticed that there is a loop area on the Top
> >>side. If I re-route some of the wires to the bottom side, will this
> >>eliminate the loop area?
> >
> >
> > The "loop area" is interesting in as far as it is a measure of how much
> > magnetic flux is linked to the loop - it is another way of saying "what
> > is the mutual inductance between this conducting loop (secondary
> > winding) and the various current-carrying loops on and around the board
> > (primary windings) that might excite it."
> >
> > Any connection that completes the loop - on either side of the board -
> > has to be taken into account.
> >
>
> thats only part of the story.

Mutual inductance is the whole story, but I agree that my choice of
words did lay all the emphasis on the loop as a receiver.

> for a start, the loop is an antenna, so its is also quite capable of
> transmitting as well as receiving - IOW it can be the "exciting" loop.

Agreed.

> then of course the inductance of the loop can (and usually does) have a
> deleterious effect on the behaviour of the associated circuit.

But there are printed circuit inductors and inductances ...

> good pcb layout can be summarised in 6 words:
>
> Current Flows In Loops. Minimise Them.

unless you are deliberately making some kind of transformer or antenna
.....

-- 
Bill Sloman, Nijmegen

.

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