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The question about ADC-----Is my analyze right?

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zyzyh

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The figure is the digital signal of ADC output in frequency domain.The input signal is 15.36MHz,and the sampling CLK is 61.44MHz.The phase noise is excellent, but the harmonic is poor! Why!?
My analyze as follow:
1\ Not the harmonic of the input signal or the CLK.Because the sampling makes the harmonic only at 0MHz\15.36MHz\30.72MHz.
2\Not the spurious signal of the input signal or the CLK.Because they are orderliness.
So, the reason of the harmonic coming is ADC.

Is my analyze right? Or what is the real reason?

Thank you!
 

Who can talk with me?!!!
 

what's the voltage of the reference?
what's the input voltage?
I think you can try anathor simulation with less input voltage.
 

and how about those at fs-n*fin?

Added after 5 minutes:

and make sure fin/fs=cycles/N when doing fft, where cycles and N are natually prime for more random and white quantization noise
 

The harmonic may stem from the INL of the ADC. usually, INL manifest itself as harmonic distortion in the ADC (it's frequency depends on the INL graph).
 

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