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ADC16DV160's dBFS specification

Tsuguhiko Asai
Expert 1260 points
Other Parts Discussed in Thread: ADC16DV160

Dear All,

Let me confirm it about dBFS specifications of ADC16DV160.
Please refer to the attached data.
"ADC16DV160_dBFS_Data@10MHz.pdf"

This is the data that our customer performed the FFT measurement of ADC16DV160 on their system.
Our customer is concerned about dBFS growing big in the range of low frequency from -90dBFS.

【Our Customer request】
dBFS < -90 :Pass
dBFS > -90 :Fail

With most cases, dBFS satisfies the request of the customer.
But, According to the part of the red letter of the table,
in the case of Fs=305Hz, FS-4dB, "-95.5dBFS" was confirmed.
(It is a value near "-90dBFS".)

May the dBFS specifications of ADC16DV160 become -90dBFS in the range of low frequency?
Best Regards,
Tsuguhiko Asai

ADC16DV160_dBFS_Data@10MHz.pdf

  • 0
    TI__Expert 4340 points

    Tsuguhiko,

    Almost all ADC's have low frequency flicker noise. At low frequencies, the noise rises up and is no longer shaped like flat white noise. The noise continues to increase as the frequency becomes lower. The observed increase in the noise near DC may be due to flicker noise, but it may also be due to the window function that the customer is using to analyze the spectrum. Is the customer using a window function (like Blackman window)? If they are not, it is very likely that this is flicker noise.

    Regards, Josh 

  • 0 in reply to Joshua Carnes
    Expert 1260 points

    Dear Joshua

    Thank you very much for your kind replay.
    Please let me confirm following.

    We think that the volume of flicker noise is related with measurement frequency,
    and is not related with input signal frequency of this IC, usually.
    Is our understanding correct?

    Otherwise, may the volume of flicker noise change when we change input signal frequency of this IC?
    (our customer's input signal frequency of this IC is 10MHz.)

    Best Regards,
    Tsuguhiko Asai

  • 0 in reply to Tsuguhiko Asai
    TI__Expert 4340 points

    Tsuguhiko,

    The low frequency flicker noise typically does not change with the analog input signal unless the noise is coming in with signal itself and and a filter is not being used.

    Unfortunately, our WaveVision 5 data capture platform can only capture up to 65k samples, so I cannot achieve better frequency resolution in the FFT to see more of the flicker noise.

    Regards, Josh

  • 0 in reply to Joshua Carnes
    Expert 1260 points


    Dear Joshua

    Please let me confirm following by addition.
    Does the volume of the flicker noise not change even if
    "amplitude" of the analog input signal of this IC changed?


    Particularly, we and the customer think about the possibility
    that by "electric current" to input into this IC increasing,
    the volume of the flicker noise of this IC increases.

    Other than "the noise coming in with signal itself",
    please tell me about the case which the volume of
    the flicker noise increases to.

     ・the "amplitude" of input signal

     ・the "electrical current" into this IC

     ・others

    Best Regards,
    Tsuguhiko Asai

  • 0 in reply to Tsuguhiko Asai
    TI__Expert 4340 points
    Tsuguhiko,
    Theoretically, the flicker noise at DC will not change significantly across analog input signal amplitude or frequency.
    Note that it IS possible that the noise at low frequency varies from data capture-to-capture. The instantaneuous power of the noise in one capture may be different than the instantaneous power in the next due to the slow change in time (low frequency). Spectral averaging is recommended to get the average noise across captures.
    It is also possible that low frequency noise observed in the spectrum near DC is coming from the power supplies. Although, the noise in the spectrum near DC that results from this noise source typically does not change with the applied analog input signal amplitude or frequency.
    Regards, Josh