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Original question:

ADS1298ECGFE-PDK: ADS1298ECG FE -PDK EVM

ADS1298ECGFE-PDK: ADS1298ECG FE -PDK EVM

vasanth kumar78
Intellectual 955 points
Part Number: ADS1298ECGFE-PDK

Hi

1.In the schematic of ADS1298ECGFE  front end circuit(see below figure )at low pass filter section diode clamped low pass filter is used ..shall i know reason behind( other than the settling time improvement).

2.if it is wrong, please correct me.normal input ECG signal frequency is 0.05Hz to 100Hz only, but in design kept is 2nd order low pass filter cut off frequency is 7kHz, if this higher  cut off frequency in the sense ,,we cannot get original signal ...please explain this point...

3. Please let me know ...what is the range of ECG signal ?..how to select range of cutoff frequency for low pass and high pass filter in front end circuit...

querry.pdf

  • 0
    TI__Guru 55042 points
    Hello Vasanth,

    Thanks for your post!

    1) A second order filter is used to increase the slope of the cutoff frequency so that high frequency signals do not alias back into the sample frequency range.

    2) Low pass means that signals with a lower frequency than the cutoff frequency will not be attenuated. 7kHz is much greater than 0.05 to 100Hz, so signals within the 0.05 to 100Hz range will not be attenuated.

    3) 0.05Hz to 100Hz to a reasonable estimation. I do not recommend adding a high pass filter to the design.

    For more information on how to select RC filter component values, you can refer to TI Precision Labs for ADCs. (Section 5 and 6)

    training.ti.com/ti-precision-labs-adcs