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ADS1292R: Respiration/Impedance Measurement Frequency Range

JanGra
Prodigy 20 points
Part Number: ADS1292R


Hey,

unfortunately, I could not find any data on the frequency range of the ADS1292R impedance/respiration signal measured.

Often there is a low-pass filter with a cut-off frequency between 2-4 Hz applied.

What is the frequency range of the respiration signal acquired? Is it generally limited to a low-frequency band under 4 Hz or can I measure frequencies above 4 Hz?

Kind regards and thanks,
Jan

  • 0
    TI__Guru 66906 points

    Hello JanGra,

    Thank you for your post and welcome to our forum.

    You are correct in saying that most applications further process this data to low-pass filter down to < 4 Hz. However, the ADS1292R does not low-pass filter the demodulated signal on the respiration channel down to 4 Hz. There is some differential low-pass filter after the PGA stage, but this cutoff frequency is about 840 Hz (internal resistor = 2k, external differential cap PGA1P->PGA1N = 47 nF). The signal bandwidth that you can measure is ultimately limited by the digital filter from DC up to about 0.262*fDATA. 

    Best regards,

  • 0 in reply to Ryan Andrews
    Prodigy 20 points

    Perfect, that would solve the issue.

    Thank you very much for the quick response.