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DC offset removal in ECG/EEG/EMG

Question asked by libuz on Apr 19, 2012
Latest reply on Jun 25, 2012 by Gustavo.Castro

I have a confusion regarding how to remove DC offset in ECG/EMG amplifer, which is said to be around 300mV. I came up with 2 different techniques:

A. Instrumentation amplifier followed by a 1st order RC high pass filter

B. Instrumentation amplifier with ac-coupling (output fed back through an integrator to the reference pin of IN-amp)

 

With both techniques, I got similar result: couldn't get higher gain than ~10. So what is the advantage of B over A ?

I found a design with high gain of 100: Figure 69 on the data sheet. But it seems like I cannot use common mode feedback as DRL.

 

Could someone suggest me how to get higher gain from IN-amp ? Can I just use a RC HPF before the inputs of IN-amp?

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