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NRF51822 PCB layout review

dingari

Hello, a few days ago I was having trouble with RF performance on a custom PCB using the NRF51822. I posted here to get feedback and figure out where the design went wrong.

I've since then re-designed the board, taking into account the faults of the previous design. Could someone review this design for any obvious mistakes / design errors before I send it off for manufacture?

Relevant part of schematic:

Schematic

PCB top:

PCB top

PCB bottom:

PCB bottom

Main changes since last time:

  • Use integrated balun instead of discrete matching network
  • Antenna on same side of PCB as SoC and matching network
  • More free antenna placement
  • RF and SoC grounding prioritized
  • Four layers (Bottom components and signals - ground plane - power traces - top components and signals)
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  • 0

    This seems much better than the initial board, but it is difficult to see all the details of the layout in the pictures. It would also be interesting to see the other planes, particularly the ground plane. Can you upload Gerber files, which would make it easier to review it?

    Also:

    • Which balun do you use? It must be one of the supported baluns. Remember to take care to copy the placement of the capacitor (your C20) exactly as the reference design.
    • Even though the antenna datasheet states that "No external matching required", this is generally only true if your board is close to identical to the antenna reference layout. In practice, most boards require a pi network in order to tune the antenna, so you should include that.
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  • 0

    This seems much better than the initial board, but it is difficult to see all the details of the layout in the pictures. It would also be interesting to see the other planes, particularly the ground plane. Can you upload Gerber files, which would make it easier to review it?

    Also:

    • Which balun do you use? It must be one of the supported baluns. Remember to take care to copy the placement of the capacitor (your C20) exactly as the reference design.
    • Even though the antenna datasheet states that "No external matching required", this is generally only true if your board is close to identical to the antenna reference layout. In practice, most boards require a pi network in order to tune the antenna, so you should include that.
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