More NFC tuning capacitors

[Salas]

Hi Support Team,

In new PS v1.1,  two more capacitors are drawn in reference circuitry, Why are they needed? And how to tune these four capacitors (CT1, CT2, CT3 and CT4) which are not described in PS and nWP026.

Regards

Salas

Nordic

[Kaja]

Hi Salas, 

sorry for the delayed response, it's been public holiday here on Norway.  

The two more capacitors are just for more flexibility. Two capacitors in parallel can be viewed as C_tot = C1 + C2, so two more capacitors gives the flexibility of choosing the most preferred capacitors. So you tune in the same way, as in the white paper. If you get that C_tune1 = C_tune2 == 130 pF, then you can choose to use 120 pF + 10 pF. 

If its just necessary with one cap, then its just an unconnected pad, and that is not a problem, so we recommend the costumers to put in pads for two caps, if they have room, but it should be enough with the original two as well. 

Best regards,
Kaja

[Salas]

Hi Kaja,

Thank you. Got it and closed the case.