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Inductor for 3rd overtone xtal

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twlin1

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I choose 2.7uH-inductor/ 1nF-capacitor for highpass filter in 3rd overtone 48MHz xtal apllication. But from the attahced figure, "L vs freq", L at 3rd overtone 48MHz is close to 5uH, which is much bigger than 2.7uH at 16MHz fundamental mode.



Is the inductor okay? Am I right in judging the inductor good/bad by the "L vs freq." for 3rd overtone xtal apllications? And when I simulate with 48MHz crystal model, which inductor value should I include?

Thanks.
 
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FvM

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I think, the "L vs freq" diagram is showing the effect of inductor self-resonancy rather than a varying inductance. The effect can be better modelled by a parallel capacitance. Because I don't know your oscillator circuit, I can't determine if the parallel capacitance matters.
 
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    twlin1

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twlin1

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I think, the "L vs freq" diagram is showing the effect of inductor self-resonancy rather than a varying inductance. The effect can be better modelled by a parallel capacitance. Because I don't know your oscillator circuit, I can't determine if the parallel capacitance matters.
My circuit is as attched figure.

My concern is that if I stand at the point 16MHz, the inductance can suppress 16MHz. But if I stand at 48MHz, the inductance seems too large to suppress 16MHz. Is my point of view right?

Or are there any other concerns when choosing inductor from so many manufacture? Thanks.
 

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