NFC antenna matching

[Mickael]

Hi there,

we are currently designing an NFC antenna for our product based on the NRF52840. 

The integration guide out of the spec is pretty comprehensive (see below)... But I still have a few questions:

• Can you confirm that Cp1 & Cp2 are parastics capacitance (of both PCB and atenna)?
• I would have expected Cint to be specified as a constant of the chip but I cant find it anywhere - Could you help us with that one too? 

  

Thank you!

Mickael

[haakonsh]

Hey Mickael,

Sorry for the delayed response.

Cp1 and Cp2 is indeed the total parasitic capacitance of the board and antenna. Cint1 and 2 is the pin/pad capacitance (4pF).

See GPIO Electrical specification Pad capacitance on NFC pads.  

Cheers,

Håkon.

[Mickael]

Hi Hakon, very clear answer thank you!