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Antenna 2,4GHz

Hello guys!

I have a curiosity regarding the components that precede the antenna in the CC2540 microcontroller according to the figure, can someone explain to me why it has to use that part?

Obs, I'm using the 2.4GHz design (AN043)

Taking advantage of the post, I would also like to know the summarized function of the two crystals present in the typical application (32 MHz and 32 kHz), read something on a frequency of 16 MHz also, this frequency of 16 MHz is an internal oscillator of the CC2540?

Thanks in advance and sorry if it was stupid questions.

  • William,

    This part uses a differential RF port, this requires the customers to have and external balun. The external balun is implemented using simple passive components, the parts are : C262, L261, C252 and L252. But before the balun we need DC decoupling and that is implemented with C251 and C261. Now the last is that we need a low pass filter to remove 2nd, 3rd and higher harmonics to enable our customers to eventually pass regulatory requirements.


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  • In reply to TA12012:

    Thank you TA12012! Now I understand the purpose of this circuit!