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Supply rails on Double sided PCB

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Advanced Member level 1
Jul 13, 2001
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Hi all,

ON a double sided PCB using split supply, I plan to keep the +ve rail on the top side, -ve rail on the bottom side and GND

on both top and bottom side.

How will the performance in terms of Parasitics of such a board be as against the one where +ve, -ve and GND all share both

the tracks.

Views welcome.


Assuming all the components are on one side of the board, I would choose to have the bottom layer as a solid ground plane, with as few tracks as possible breaking up the area.

In my experience it is very often hard to allocate a nearly-unbroken ground plane on a 2 sided PCB. Therefore I have often used one of two approaches:

- On a purely digital board/digital areas, try to make the grounding to a network with as small "holes" as possible. In other words, connect GND to GND whenever possible. To give good return path to high speed signals the loop area between those signals and ground should be as small as possible.

- On analog board, separate high amplitude circuits and sensitive circuits by having the local grounds for each of them separate in great degree, and interconnect the grounds with thought for where gound is carrying high/fast currrent and where a sensitive signal has its reference. Then interconnect so that distrbing high amplitude ground currents will not go through the sensitive parts' ground areas.

And do not forget the bypass capacitor returns - those loops are also critical!

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