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DPing
DPing
Associate
November 22, 2018
Solved

Which is the typical value of the matching impedance that the ST25R3911B should see?

  • November 22, 2018
  • 1 reply
  • 766 views

I'm designing the NFC antenna, the EMC filter and the matching circuit, for an industrial NFC application. I'm looking for a good value of the matching impedance that provide the right tradeoff between performance and efficiency

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Best answer by Travis Palmer

​Hello,

The target matching impedance is commonly chosen by the available power budget - the power you want to spend when the reader is transmitting.

If there is no special power budget defined and there are no special requirements about read range, then a good target is around 20 to 30 Ohm. This should give a power consumption between 170mA and 140mA during constant wave.

Br Travis

1 reply

Travis Palmer
Travis PalmerBest answer
ST Employee
November 23, 2018

​Hello,

The target matching impedance is commonly chosen by the available power budget - the power you want to spend when the reader is transmitting.

If there is no special power budget defined and there are no special requirements about read range, then a good target is around 20 to 30 Ohm. This should give a power consumption between 170mA and 140mA during constant wave.

Br Travis

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