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I have to design a bio potential measurement system:

  • AD converter and the connecting digital / software part
  • an analog amplifier stage: basically a regular ECG amplifier composed of discrete instrumentation amplifier

Googling around I see that the instrumentation amplifier's reference input is driven by a miller integrator feedback.

My question is: what is the purpose / advantage of this miller integrator feedback?

I think, remove DC component can be easy in software side, hardware cost, size, complexity and PCB design can increase dramatically.

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  • \$\begingroup\$ Can you post a link or schematic of exactly what you're talking about? You might be talking about Driven Right Leg -- I don't think so, but I'd like to make sure. \$\endgroup\$
    – Scott Seidman
    Commented Nov 21, 2019 at 13:54

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The purpose is to keep the DC bias voltage in a range that the instrumentation amplifier can handle. Without it, the amp could easily saturate and you'll lose your signal.

The reason that the servo configuration is used is that it makes it much easier to create a high-pass filter with a low cutoff frequency with reasonable size components.

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