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Question about layout

Deepa Mannath
Prodigy 300 points

Other Parts Discussed in Thread: WL1835MODCOM8B

The layout files in the link show the COM8 module. This module has a trace antenna and a provision for chip antenna. But based on the layout the chip antenna location is very difficult for us to achieve. Is that the only suggested layout pattern?

 Are there any suggestions/design guidelines for using Chip Antenna only?

:  http://www.ti.com/lit/ug/swru359c/swru359c.pdf

 The layout files are listed here: http://processors.wiki.ti.com/index.php/WL18xx_Evaluation_Platforms#Board_Design_Documentation

 

  • 0
    Expert 2765 points

    Hello,


    To add to Deepa's post, can we also get layer stack up information.

    Thank you

    Regards

    Santhosh

  • 0
    TI__Prodigy 720 points

    Hi,

    The WL1835MODCOM8B Layout is the reference design for the module.

    The trace is optimized for 50 R routing and the antenna is located far from the device in order to have enough isolation from the second one for MIMO operation.

    Please explain what does " difficult to achieve" means?

    Regards,

    Alexey 

  • 0 in reply to Alexey Berd
    Genius 3320 points

    Alexey,

    "Difficult to achieve" means that the trace for the antenna is very long and makes it challenging to mimic that same board real estate on a real product.  Are you available to have a discussion on the layout for this module?  I would like to have a discussion.  Please email Jason.Haedt@avnet.com and we can setup a time to review layout questions.

    Thank you for your time,

    Jason Haedt

  • 0 in reply to JasonHaedt
    Expert 2765 points

    Hello Alexey,

    To add to Jason's comment:

    1. We are unable to match the current layout of the COM8 module due to space constraint. Also the module seems to use trace antenna, which (I'm not sure) is not FCC certified?

    2. If we plan to use a chip Antenna, how should we proceed in terms of layout? Do you have a reference design that is FCC certified so that we can use the same Antenna and design. This will mean that we only need to perform a minimum set of FCC testing/qualification.

    3. Can we get the layout and stack up information for the design?

    4. Also you mentioned MIMO - we plan to use 1801 - how can we use MIMO in this case? When I read through the datasheet, it showed one antenna output.

    Thanks for taking the time to reply back.

    Regards

    Santhosh

  • 0 in reply to Santhosh Ramani
    TI__Prodigy 720 points

    The COM8 design is using chip Antenna and it's certified:

    http://processors.wiki.ti.com/index.php/WL18MOD_Product_Certification

    You can shorten the trace of the main antenna up to the module and place the antenna closer

    The stackup is 4 layers 1.52 mm board - layer 2 is RF reference layer.

    The COM8 was designed as a superset for both MIMO and SISO desings.

    1801 is SISO only - the main antenna is ANT1 on the com8 board (the long trace one) and you can shorten it and get a permissive change from FCC.

    Alexey 

  • 0 in reply to Alexey Berd
    Expert 2765 points

    Hello Alexey,


    Thanks for the information and the detailed explanation. I do have quick question for you - can you please let me know the current consumption on the 1.8V rail (VIO).

    I am trying to use the PMIC which has a max current of 100mA and wanted to know if that will suffice. I was not able to find this information in the datasheet.

    Thank you

    Regards

    Santhosh

  • 0 in reply to Santhosh Ramani
    TI__Guru* 85400 points

    Hi Santhosh,

    The vio current should support up to 200mA.

    Regards,
    Gigi Joseph.