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  • Re: Reply To: Class 3 antenna design guide

    5. February 2019 at 19:20
    in reply to: Class 3 antenna design guide
    The inductance should be measured without any matching components(should be disconnected from chip also). After the inductance of the coil alone is determined, then use the formula for resonant frequency to determine the required C value.
    If the inductance is too low and does not provide resonance at ~13.56MHz using the internal capacitor.can you explain me little bit
    In regards to my statement about inductance too low or high, let me explain.
    If inductance is too high, lets say 4.5uH for example, it is not possible to resonate at 13.56MHz. The closest you could get would be ~12.68MHz, since we have 35pF internal capacitance. Formula is 1 / 2pi*sqrt LC. Adding external capacitance will bring down the resonant frequency, so the only way to tune this to proper resonance is by decreasing the inductance(remove turns and/or make the traces thicker).

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