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Original question:

ADC3424: Guide to use LMH6518 to drive ADC3424

ADC3424: ADC3424 noise in the input channel

Lin_Charles
Expert 4260 points
Part Number: ADC3424

Hi team,

    We are penetrating our AMP+ADC solution to my customer. And we find that some noise is monitored in VIN+A and VIN-A pin when no signal is fed into ADC, see the red and blue curve. And the frequency is 100MHz, the same frequency as the clock to ADC. Could you please help figure out why the clock will affect the input signal and how to eliminate the influencec? Thanks. 

  • 0
    TI__Genius 12780 points

    Hi Charles,

    Could you please provide the schematic? Is this noise coupling onto all of the analog inputs, or just CHA? If so, is the noise amplitude the same across all 4 channels?

    I am looking into this further on the evaluation module, and will be back with you soon.

    Best Regards,

    Dan

  • 0 in reply to dBrock
    TI__Expert 4260 points

    Hi,  Dan

       We saw this waveform in ALL channels and I am wondering this noise may come from clock, but I cannot find reason. Also I am thinking that this as offset voltage of ADC, I am not sure if it is right. Hope to get your feedback soon. Thanks.

  • 0 in reply to Lin_Charles
    TI__Genius 12780 points

    Hi Charles,

    Is this on the ADC3424EVM, or is this a custom PCB? I am not seeing this noise on my EVM, but will try with a higher bandwidth scope and get back with you.

    Are you able to disconnect the FDA outputs and probe ADC inputs?

    Best Regards,

    Dan