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CC2540 without balun?

Matjaz Tome
Prodigy 130 points
Other Parts Discussed in Thread: CC2540

Hello!

We are developin product with CC2540. On our prototype PCB there is footprint for this balun: http://www.mouser.com/ds/2/400/e721_multibpf_balance_dea07-15120.pdf

Problem is, the footprint is incorect and balun can't be solderd to the board. Can prototype be expected to work without this balun with range of only few centimeters?

  • 0
    TI__Guru 56590 points

    Hello Matjaz,

    If you do not mount the balun you will need some form of transformer to change from differential (two lines from chip RF_P and RF_N  which is out of phase with each other of 180 degrees) into a combined unbalanced line ( alter the phase of the two lines to match and combine).

    Just to get a link up and running at a few you can read this note for inspiration:

    http://www.ti.com/general/docs/litabsmultiplefilelist.tsp?literatureNumber=swra421 

    And create a simple dipole wire antenna and connect to each of the two terminals. However this might not work at all if you end up with a very mismatched antenna in which case most of the signal fed to the antenna will reflect back towards thee chip. Then the antenna will radiate very little signal and the reflected signal will interfere with the original signal transmitted from the chip which can cause high distortion and harmonic emissions and will be in conflict with regulations etc..