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input filter ads1298 and group delay

Other Parts Discussed in Thread: ADS1298, ADS131E04, AFE4400

Dear sir,

What kind of input filter would you recommend me to use for the ADS1298  (or ADS131E04).

I want to measure a heart rate, let say between 2 and 6 Hz. The heart rate is measure with an infra red led and a light sensor. The light source is only on during a quarter of the time! 2,5 ms on and 7,5 ms out.  So the group delay of the filter should be very small

Regards JPMH

  • Hello JPMH, 

    From the description of your application, it seems that your goal is to measure heart rate only and not the electrocardiogram (ECG), is that correct?

    I suggest that you look at the AFE4400 first. This device has integrated LED drivers, a transimpedance amplifer, and a 22-bit delta-sigma ADC, making it very useful for low-cost optical Heart Rate and Pulse-Oximetry applications.

    On the other hand, the ADS129x family is better suited for ECG applications. ECG is a differential signal acquired by connecting electrodes to the body (IR light is not used).

    If Heart Rate is the only measurement in your application, I think the AFE4400 would be a more suitable device.

    Best Regards,