NFC06A1 matching circuit impedance

[JGreve]

Hello :)

Does anyone know what the impedance of the existing antenna matching circuit on the X-NUCLEO-NFC06A1 board is? I can't seem to find that information in any of the datasheets. I need the impedance so that I can design a new custom antenna. 

Br. Jørgen

[Travis Palmer · Accepted solution]

Hello Jørgen,

The X-NUCLEO-NFC06A1 features AAT. AAT can change the matching impedance in a certain perimeter dynamically. AN5322 provides additional information about the AAT feature.

By setting the register 26h and 27h the matching can be changed from minimum to maximum.

Reg. 26h= 0x00; 27h = 0x00: (minimum)

Reg. 26h= 0x82; 27h = 0x82: (nominal)

Reg. 26h= 0x82; 27h = 0x82: (maximum)

By default the nominal matching is applied.

For acting only as a NFC reader AAT can be removed and a fixed matching applied.

BR Travis