NFC Tuning and Input Resistance Intuition

RE: NFC Tuning and Input Resistance Intuition

Jared — Mon, 17 Jun 2024 13:32:37 GMT

Hi,

I just checked with our HW designers and this is what they said:

Looking at the RTL and the Design Description of the digital part, increasing the register value lowers the input resistance. So the whitepaper is correct.

meaning to decrease the voltage swing you would have to increase R_IN.

regards
Jared

RE: NFC Tuning and Input Resistance Intuition

bdub94 — Mon, 17 Jun 2024 02:53:25 GMT

I'm not following -- the diagram shows a shunt resistor. Do you have another schematic that shows an equivalent series resistor?

After further searching, a comment in the following post states "the higher the value of R_in is, the lower its value in Ohm is."

nRF52 NFC communications

Is this statement correct?

RE: NFC Tuning and Input Resistance Intuition

Jared — Fri, 14 Jun 2024 12:07:41 GMT

Hi,

Increasing the R_IN will increase the effective series resistance, which will decrease the current flowing into the circuit which reduces the voltage swing. Decreasing R_IN will increase the current flowing into the circuit which will increase the voltage swing.

regards

Jared