Picodev rfid module matching circuit

Hello, I have just watched the piicodev Rfid module design video trying to understand how the board works under the hood. I was wondering how you calculated the capacitances for the matching circuit because when I plug in the values from the provided schematic into the datasheet formulas It doesn’t seem to bring the same values for C1a, C1b, or C2a and C2b. Here are the formulas I used

I plugged in L=470nH, f=13.56, and R=0.3 Ohms. Could you please explain how you got the capacitances?

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Hi @Rhyl249253 - wecome to the forums :smiley: This one gets right down into the weeds!

@Peter was the engineer for this project so I can only tell you what I recall of the process.
If I recall correctly - the formulae were great for getting a starting value for components in the matching circuit in an ideal sense. However, additional factors introduced by eg. board geometry, arrangement of components etc. meant that a better value could be found empirically.

We started with the ideal values and then ran several tests with components in the near vicinity to optimise for better range.

That’s all I can recall for now. I hope that clears up the discrepancy
Are you working on your own RFID reader/writer?

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Yes, I am trying to see if I can design a custom one for a class project I have.So I have to understand it well. Thank you very much for replying. Incase you have the initial calculations please do share

@Rhyl249253 - sadly not :person_shrugging: I’ve had a root around the original project directory and it looks like that original work is lost to the annuls of time.

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Okay.Thank you though