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  • TI Thinks Resolved

ADS1298ECGFE-PDK: problem with front end filter design

Part Number: ADS1298ECGFE-PDK

i have made a 2nd order low pass front end for ADS1298 ECG application. 

now please someone tell me that weather this is correct for ECG or not.

  

  • Hi Ahmed,

    Welcome to our e2e Forum! Can you grab a snapshot of just one filter section? It's had to make out the compoment values in the screen shot you provided.

     

    Regards,

    Tom

  • In reply to Ahmed Qureshi41:

    Hello Ahmed,

    What is the value of the second resistor, 'R'? From the first image you posted, it looks like it was supposed to be 120k.

    I simulated the response of this low-pass filter and the -3 dB bandwidth is around 44 Hz. I would recommend increasing this at least 10x or more so that you do not attenuate the ECG bandwidth of interest. Remember that these filters are primarily used for antialiasing purposes and that additional filtering can always be done digitally.

    Best Regards,

    Ryan Andrews

    Precision ΔΣ ADCs

  • In reply to Ryan Andrews:

    please suggest me then what value of resistor and capacitor we will use that our ECG signal is not attenuated.Can i use first order LPF for that.

    tell me each thing with detail

  • In reply to Ahmed Qureshi41:

    Hi Ahmed,

    ECG signals typically exist between 0.5 Hz and 40 Hz for consumer-grade applications and can extend up to about 150 Hz or so for medical-grade applications.

    The selection of the R-C components is up to you to design. Typically, the resistor values are chosen first since they also provide DC current-limiting protection, which is also a requirement for medical applications. The total resistance can range from 30k to 100k and can be separated into two resistors to act as a secondary fault protection. Once the resistors are chosen, the capacitors are then selected accordingly to set the desired low-pass filter cutoff frequency.

    You can find plenty of examples on our forum as well as in the User Guide for the ADS1298ECGFE-PDK.

    Best Regards,

    Ryan Andrews

    Precision ΔΣ ADCs

  • In reply to Ryan Andrews:

    i am stuck with it and cannot find solution for it so please tell me How to decide what kind of filter i should use, i am not clear with your review so
    plz tell me in detail. i am BS student not professional.

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