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ADS1299-4: Question for the datasheet

Sara Jia
Expert 2975 points

Part Number: ADS1299-4
Other Parts Discussed in Thread: ADS1299

Dears,

    I can not understand  P16 in in the datasheet(8.1 Noise Measurements),in table1,  μVPP=7μVRMS, Would you pls tell me how the result come out? Because in my opinion, μVRMS=0.7 μVPP.

  Would you give some material for FECG Design? 

  • 0
    TI__Guru**** 182761 points
    Hi Sara,

    I will try to find you the details on the calculations used for the ADS1299-4 tables, in the meantime, we do not have any reference design material specifically related to fetal ECG.
  • 0 in reply to Tom Hendrick
    Expert 2975 points

    Dear Tom,

      Any update?

  • 0 in reply to Sara Jia
    TI__Guru 68966 points

    Hi Sara,

    The formula you are familiar with is used to convert the peak amplitude (not peak-to-peak) of a sine wave to its RMS amplitude (officially, it's 1/sqrt(2) * Vp). When measuring broadband ADC noise, we are looking at a Gaussian distribution of a number of samples. In this case, the RMS noise refers to 1 sigma or the "standard deviation" of the collected samples. Either 6 sigma or 6.6 sigma is generally used to define the peak-to-peak amplitude as this includes 99.7% or 99.9%, respectively, of the collected samples. In the ADS1299, it appears that 7-sigma was used as the peak-to-peak noise value.

    Best Regards,