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I'm working on a 2 layer PCB with very poor grounding. I want to improve it but I'm a little lost. Basically the PCB as a DC input, a couple of buck converters and some communication signaling like USB, UART, etc that goes to connectors for external devices.

There are no controllers, procesors or RF devices on the board.

Any tips, ideas, application notes, books, etc would be greately appreciated.

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    \$\begingroup\$ No controllers or processors and you have USB / UART? \$\endgroup\$ – kenny Aug 2 '12 at 15:27
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    \$\begingroup\$ Can you add a screen shot of the schematic and PCB layout ? \$\endgroup\$ – Rocketmagnet Aug 2 '12 at 15:33
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    \$\begingroup\$ Henry Ott has some great advice about ground planes. Grounding of Mixed Signal PCBs \$\endgroup\$ – Rocketmagnet Aug 2 '12 at 15:41
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    \$\begingroup\$ How do you know the problem is grounding? \$\endgroup\$ – Brian Carlton Aug 2 '12 at 16:10
  • \$\begingroup\$ USB / UART are just passing through the board to external devices. \$\endgroup\$ – Gustavo Corona Aug 2 '12 at 17:59
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I would give the switchers their own small ground plane which you connect at 1 point with the PCB's ground plane. No traces through the switchers' ground planes.

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  • \$\begingroup\$ you mean he should isolate the switchers gnd and the rest of the board gnd? is this a better technique generally ? \$\endgroup\$ – Abdella Aug 2 '12 at 22:49
  • \$\begingroup\$ @Abdella - Not completely isolate, all grounds should be connected. But create local ground islands for them yes. I don't know if this is done in general, but in my designs I found that it causes less EMI. \$\endgroup\$ – stevenvh Aug 3 '12 at 4:54
  • \$\begingroup\$ ah ok. And how do you know it causes less EMI? How do you measure it? \$\endgroup\$ – Abdella Aug 3 '12 at 14:19
  • \$\begingroup\$ At work we have (expensive!) equipment for that, in a purpose-built Faraday cage. We can do the same tests required for EU-compliance. \$\endgroup\$ – stevenvh Aug 3 '12 at 14:30
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    \$\begingroup\$ @Abdella - For instance this one, between 25000 and 30000 euro. More info. \$\endgroup\$ – stevenvh Aug 3 '12 at 14:44
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A Perfect PCB design must follow the basic rule.

For power lines connections, you must consider the maximum current can draw from that connections. Also keep in mind that dept of PCB copper layer is too important.

It seems that you are using only 5V VOLTAGE line and power is not more than 1A. For this your track thickness mest not be less than 2mm depending upon the dept of PCB copper layer. And this will be same for GROUND connections.

It is suitable to use all empty space of both layer sides of PCB as GROUND. This will prevent proper ground and will help if you your PCB is dealing with Communications signals like UART, Ethernet and USB etc.

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