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Optimum rf impedance to present to transceiver output.

I am tying to match the nRF52840 rf output to my 50 ohm 2.45GHz pcb antenna.  What is the optimum rf impedance for best transmitter/receiver performance?  The markings on the chip are N52840 QIAAC0 1908GK. 

Thankyou,

Doug

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  • Hello Douglas,

    The optimum impedance for best transmitter/receiver performance is 50 ohms.

    The components in the radio matching network are there to subdue harmonics and make sure that the signal in the transmission line is close to 50 ohms impedance. There isn't a guarantee that the signal out from the ANT pin is 50 ohms impedance (it's usually a bit above), and the radio matching network is there to adjust it. The same goes for the antenna matching network, it's there to make sure that the signal sees as close as possible to a 50 ohm impedance into the antenna. 

     

    Having close to 50 ohm impedance for the entire RF path facilitates an optimal transfer of energy, and if there is a mismatch in impedance you get a loss in power and reduced performance.

    We provide a service of schematic and layout review to help our customers get an ideal PCB layout as well as in house antenna measurement and tuning.

    You can share your schematic so I can see if you need to do any changes to the design (I have made the case private so no one else can see them), and when/if the PCB is ready you can send PCB's to us and we can do measurements in-house to give you recommended component values for the matching networks.

    Best regards,

    Martin S.

Reply
  • Hello Douglas,

    The optimum impedance for best transmitter/receiver performance is 50 ohms.

    The components in the radio matching network are there to subdue harmonics and make sure that the signal in the transmission line is close to 50 ohms impedance. There isn't a guarantee that the signal out from the ANT pin is 50 ohms impedance (it's usually a bit above), and the radio matching network is there to adjust it. The same goes for the antenna matching network, it's there to make sure that the signal sees as close as possible to a 50 ohm impedance into the antenna. 

     

    Having close to 50 ohm impedance for the entire RF path facilitates an optimal transfer of energy, and if there is a mismatch in impedance you get a loss in power and reduced performance.

    We provide a service of schematic and layout review to help our customers get an ideal PCB layout as well as in house antenna measurement and tuning.

    You can share your schematic so I can see if you need to do any changes to the design (I have made the case private so no one else can see them), and when/if the PCB is ready you can send PCB's to us and we can do measurements in-house to give you recommended component values for the matching networks.

    Best regards,

    Martin S.

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