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ADC3664: About the SNR on datasheet

Liu Yang
Expert 5915 points
Part Number: ADC3664

Hi Team,

Please help answer the following questions.

1) is the SNR calculated by analyzing FFT data after the A/D conversion?

2) the signal input to A/D is the signal from the measuring instrument(e.g. Signal Analyzer or Signal Generator)?

    I mean whether the SNR of the input signal is clean.

Best Regards,
Tom

  • +1
    TI__Expert 8901 points

    Hi Tom,

    1) Yes, SNR is calculated using the fundamental power and noise power from the FFT spectrum. We use HSDC Pro to display the FFT and calculate the SNR. Page 70 in section A.5.2 of our user guide describes this calculation: 

    "SNR is calculated as the difference between integrated fundamental power (fundamental power, including its neighboring bins) and the noise power. The noise power is calculated, excluding the fundamental and its neighboring bins, harmonics, and custom notch frequencies. The neighboring bins of the harmonics are excluded if the GUI menu option - Notch frequency bins - Harmonic/Spur Power Calculation method is Integrate." 

    https://www.ti.com/lit/ug/slwu087d/slwu087d.pdf 

    2)  It is recommended to use a clean signal source for an analog input to the ADC and for the input clock. This will optimize the performance of the device by reducing any noise / jitter that could be introduced into the system (which would degrade the SNR of the spectrum). 

    Regards, Amy