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RF matching. How to calculate elements for network?

Associate II

Hi all,

As you know, Nucleo -WL55JC1 activates both Hi and Lo Power modes for Tx. I reviewed the matching network for both Hi and Lo Power P.A outputs and filtering and matching elements values(capacitors & inductors) are not associated with calculating formulas given in AN5457. Therefore, I do not know what is the approximate P.A output impedance determining the specific matching network.

What is the maximum attenuation that would be inserted from the filtering/matching network between P.A output and antenna socket when this circuit resonates at 868MHz?

For my business case, I want to provide an average optimal TX power output of 17 dBm before the antenna. So, if we attach a helical antenna(50Ohms) with its gain of 3dBi, the accumulative total radiated power will be 20 dBi(EiRP). Because of range of P.A TX power in Hi mode varies from 15dBm up to 22 dBm, I will centralize(maximum resonance) the TX power at 17dBm@868MHz and manage low losses mismatching as much as possible for down side and up side TX power around 17dBm.

I am a little bit confused about how to calculate the elements(capacitors&inductors) for matching/filtering network following AN5457 document.

Best Regards,