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Original question:

ADC3222 DC Spec

ADC3222: NSD at very low frequency spec

David Dobrin
Prodigy 50 points
Part Number: ADC3222

Hello,

The datasheet specifies that this ADC does have a "chopper" function to improve 1/f noise.

Yet I can't find specification of how good it is with chopper enabled.

The provided graphs do not have good enough resolution.

Can you advise what is the NSD @F=1KHz?

Regards,

David.

  • 0
    TI__Genius 9071 points

    Hi David,

    I am checking on this and will get back to you to tomorrow.

    Regards, Amy

  • 0 in reply to Amy
    TI__Genius 9071 points

    Hi David,

    The balun on our EVM has a minimum frequency of 500 kHz, so I was only able to test this with an input of 750 kHz using our ADC3222EVM. Chopper Disabled (left) and Chopper Enabled (right) - NSD is listed in the capture specs.

    Regards, Amy

  • 0 in reply to Amy
    Prodigy 50 points

    Thanks.

    Maybe you can zoom in to the relevant region, 0-1MHz?

    So that the corner frequency would be visible.

    would you expect the 1/f noise to be affected by the properties of input signal (amplitude , frequency...)?

    Regards,

    David.

  • 0 in reply to David Dobrin
    TI__Genius 9071 points

    Hi David,

    Yes 1/f noise can be affected by the input signal, especially if it is not properly filtered. Power supplies can also be a source of 1/f noise. 

    I zoomed in on the plots to better see the impact at lower frequencies:

    Chopper Disabled (left) and Chopper Enabled (right)

    Regards, Amy