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CC2520: CC2520: Ref design with 0.15-0.17mm between TOP and GND plane

Intellectual 360 points

Replies: 5

Views: 39

Part Number: CC2520

The refdesign CC2520EMK is a two layer design with 0.8mm between TOP and GND plane.

Our PCB there the CC2520 is used is a six layer with 0.15mm between these two planes.

Can you please investigate if there are a ref-design with 0.15 or 0.17 instead of 0.8mm?

We have big problems to get the power out to the antenna. The EMV value of the Zigbee is bad. Difficulties finding the right values in the Discrete balun when the distance is 0.15 instead 0.8mm.

It is even harder when we can not find Differential impedance at the output 17 and 19 of the CC2520. We have found it in a datasheet from Johanson! and not in CC2520 see attached picture below. In your CC2500 it is easily found also see below.

So two questions to you:

  • Can you say that this differential value is the right value 35-j43ohms? The one found in the datasheet of the Joahanson Balun?
  • Do you have a reference design of CC2520 with to 0.15mm to the GND plane?

Best Regards

Per Fager 

NIBE AB

  • Genius 16900 points

    Hi Per,

    If you are using the t-line inductors as used in original design with two layers then this will have problems if the GND plane reference is changed from 0.8 mm to 0.15 mm.

    Can you use discrete components instead of the t-line integrated inductors ?

    Regards,

       Richard

     

  • Genius 16900 points

    In reply to RGW:

    CC2520 is not a linear amplifier where optimum gain is achieved when the load is the complex conjugate of the amplifier output impedance. The optimum load impedance is found utilizing load pull techniques and then verified by tuning and measurements.

    The load should be close to 70+j95 in the band 2405-2480MHz band.

    Regards,

       Richard

     

  • In reply to RGW:

    Hi Richard

    Thanks for the fast answer!

    The product are already on the field. So we hoped to fix this impedance problem by changing values on the capacitors within the Balun. It seems difficult.

    We have to high EMV getting not acceptable when we transmit over 0 dbm it is over 4%. 

    /Per

  • Genius 16900 points

    In reply to RGW:

    Approx load impedance:

    CC2500: 80 + j74

    CC2520: 70 + j95 (Impedance has changed slightly from CC2500)

    //Richard

     

  • In reply to RGW:

    Thank you!

    Will take this new value into to our calculation program, simulating the Balun, and after that the 3-port VNA.

    We have tried with 35-j43

    //Per

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