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Original question:

CC2564MODA: Schematic & Layout Checklist

CC2564MODA: CC2564MODA layout requirements to preserve modular FCC certification

Engineer1
Intellectual 660 points

Part Number: CC2564MODA
Other Parts Discussed in Thread: CC2564MODN,

The CC2564MODA module has an integrated antenna, hence there is no RF trace on the PC board which the module is soldered to. I would think that module has its own multi-layer PCB with its own ground plane under the CC2564B, is that correct? Therefore it is not dependent on a ground plane on layer 2 with a substrate dielectric of 4.2 and substrate thickness of 10 mils as is required for the CC2564MODN, is that correct?

Thanks,

Brian

  • 0
    TI__Genius 13710 points
    Hi Brian,

    Yes you are correct on the above. In order to meet the FCC requirements for using the MODA, you need to follow the integrators instructions on using the module. This can be found in the CC2546MODA datasheet starting on page 26 (section 6.2.1.3.2). It provides details of the grounding of the module, where the module with antenna should be placed on the host PCB, as well as some other recommendations on signal routing to the module.

    Note that the host PCB under the MODA antennas has no metal under it. It is all etched away.

    I hope this helps.

    Thanks,
    Riz
  • 0 in reply to Rizwan Murji
    Intellectual 660 points
    Riz, thanks for the post. It was not clear whether the critical 4-layer stackup of section 6.2.1.1 is also required for the MODA, it sounds like it is not. It seems that the most important host PCB layout requirement is to keep all layers clear (no copper) near the antenna of the MODA in the region specified. One of the bullets of section 6.2.1.3.2 states to "Follow the ground guidelines described in Section 6.2.1.4". Section 6.2.1.4.1 discusses power trace among other things which I do not question, but section 6.2.1.4.2 states that "The common ground must be the solid ground plane in Layer 2". Since the MODA has its own ground plane under the CC2564B and the RF trace leading to its antenna, it seems that another ground plane underneath its own ground plane would not be required. Our layer 2 is not 10 mils below layer 1 and it does not have a controlled dielectric of 4.2, but that should not matter using the MODA. It also should not matter, I believe, that our layer 2 is not a board-wide dedicated ground plane, although we can have mostly ground plane in the area of the module. What I am asking for is confirmation that the statement of a "solid ground plane in layer 2" in section 6.2.1.4.2 is critical to the MODN but not to the MODA, since the MODA has its own ground plane and controls all the impedances between its CC2564B and its antenna. It should not require a dedicated board-wide ground plane on layer 2 of the host PCB.
  • 0 in reply to Engineer1
    TI__Genius 13710 points
    Hi Brian,

    you are correct that the number of layers and the material dielectric constant under the module is not important. The only difference between the MODA and the MODN is that for the MODA the substrate contained within the MODA is extended to accommodate the PCB antenna. Otherwise the actual module itself is the same.

    Having said that the material of the host PCB (where you mount the module) is not critical. It can be any number of layers you require for your application and dielectric constant of the material is not a concern. the purpose of the GND under the module is for thermal dissipation as is the via pattern suggested. It is still our recommendation to have GND under the module as much as possible and to route an signals you need to cross around the module around it. The GND under the module is not related to RF performance...

    I hope this helps.

    Thanks,
    Riz
  • 0 in reply to Rizwan Murji
    Intellectual 660 points
    Thanks Riz, this fully answered my question.