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Why is there a difference in RF tuning component configuration between QFN (pi network) and WLCSP (T network) package?

Akshay

Hi,

We have been using nRF52840 in QFN package in a BLE application. Due to size considerations, we want to upgrade to the WLCSP. I saw that the tuning network is different for both the packages.QFN packageWLCSP

This thread suggests it has to do with the tuning network.

I am using a chip antenna (2450AT42B100 and 2450AT18D0100) and a Pi network to tune the antenna. My question is, do I need to change the tuning network to T if I want to use this package?

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  • 0

    Hi Akshay,

    the matching network is for the radio, you have to add a extra matching network for your antenna.
    The different matching networks for the different packages is optimized for that packages and I would recommend you to change it, the type placements grounding of the components are important to achieve desired output power and low enough harmonics. 
    The components values will have to be tuned for your specific design. 

    Best regards,
    Kaja

  • 0 in reply to Kaja

    Thank you Kaja for your quick response.

    Just to double check, there should be two matching networks? One for the Nordic and the other for the antenna that will be used?

    Component values for which matching network need to be tuned for my design? Both or just the antenna matching network?

    We have been using just one matching network (only for antenna), do you have any idea how much performance improvement (approximately in %) we will get by adding the recommended matching network?

    Thanks

Reply
  • 0 in reply to Kaja

    Thank you Kaja for your quick response.

    Just to double check, there should be two matching networks? One for the Nordic and the other for the antenna that will be used?

    Component values for which matching network need to be tuned for my design? Both or just the antenna matching network?

    We have been using just one matching network (only for antenna), do you have any idea how much performance improvement (approximately in %) we will get by adding the recommended matching network?

    Thanks

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  • +1 in reply to Akshay

    Hi Akshay,

    Akshay said:
    Just to double check, there should be two matching networks? One for the Nordic and the other for the antenna that will be used?

     - Yes that is correct, but dependent on what antenna you use, which type of antenna have you used in the pass and what antenna are you planning to use? 
     

    Akshay said:
    Component values for which matching network need to be tuned for my design? Both or just the antenna matching network?

     - Yes both, when it comes to the once in the reference design for the radio, the point is to match the output impedance to 50 Ohm, achieve desired output power and low enough harmonics to pass certifications. 

    Akshay said:
    We have been using just one matching network (only for antenna), do you have any idea how much performance improvement (approximately in %) we will get by adding the recommended matching network?

     - No I don't  have a % of how much improvements it will give, but I don't know how you have been testing and matching the antenna in the pass, if you have also looked at output power and harmonics as well? 

    General impedance matching, again dependent on chip and type of antenna: 


    Best regards,
    Kaja

  • 0 in reply to Kaja

    Thank you Kaja!

    This all makes sense now. We will update our designs to match the reference design closely.

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