Digital Filter Design Approach

[BlackMelon]

Hello,

I'm reading the attached pdf file. I don't understand the design approach (yellow-highlighted). Could you please explain?

Thank You,
BlackMelon

 

[Harald Kapp]

I know it is no help but I don't understand that either

 

[Audioguru]

An ECG signal has DC baseline drift caused by muscles in the patient and mains hum interference picked up by the patient's body. Then most ECG circuits use the common-mode DC and AC interference signal produced by the instrumentation amplifier IC, invert it and feed it to the patient (usually to the right leg) to cancel the interference. Then a filter might not be needed or it can be simple.