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ADS1293: Cut off frequency of ECG sinc filter

Takumi Suzuki1
Mastermind 8610 points
Part Number: ADS1293

Hi,

Please let me know the cut-off frequency of ECG sinc filter.

There describes about settling time of "t s-ecg" on the datasheet page 18 as below.

I would like to know the cut-off frequency in case of this settling time "t s-ecg".

Sorry for my basic question.

Best Regards,

  • 0
    TI__Guru 66466 points
    Hello Takumi-san,

    Thanks for your question.

    The bandwidth of the digital sinc filter is specified for both PACE and ECG channels in Tables 8 - 11. I believe this bandwidth corresponds to the -3 dB bandwidth. As you can see, the final output data rate depends on the selected filter decimation ratios (R1, R2, and R3) as well as the delta-sigma modulator sampling rate (either 102.4 kHz or 204.8 kHz).

    The settling time for the ECG channels appears to be 5 output samples based on Equation (8). The data rate period can be expressed as the modulator period (1 / fs) times the oversampling ratio (OSR = R1 x R2 x R3). So, tECG = [R1 x R2 x R3 / fs]. The settling time in response to a step input is calculated as: ts-ECG = 5 x tECG = 5 x [R1 x R2 x R3 / fs].

    I hope that's a bit more clear. Let me know if you still have any questions.

    Best Regards,
  • 0 in reply to Ryan Andrews
    Mastermind 8610 points
    Hi Ryan-san,

    Thank you so much for your kind explanation!
    I understood well.

    Best Regards,