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Q&A DC offset correction loop (DC servo loop). What's its advantage, compared to a high-pass RC filter?

Once in a while in literature I see a DC offset subtraction loop. Here are a few more examples. DC servo loop removes a DC offset after an op-amp. DC servo loop removes DC current from a photo...

2 answers  ·  posted 12mo ago by misk94555‭  ·  edited 9mo ago by misk94555‭

Question DC opamp integrator
#3: Post edited by user avatar misk94555‭ · 2023-07-27T16:43:47Z (9 months ago)
  • Once in a while in literature I see a DC offset subtraction loop.
  • ![instrumentation amplifier with a DC servo loop](https://electrical.codidact.com/uploads/ng4zzswvqxkoeigxwqoxd2jt61x2)
  • Here's [another example](https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/el.2014.2262) where a DC servo loop removes a DC offset after an op-amp.
  • What are the advantages of such DC offset removal loop, compared to an RC high-pass filter?
  • The RC filter would look like this.
  • ![instrumentation amplifier followed by an RC filter](https://electrical.codidact.com/uploads/6ahuncfpoqsph4lj468pubw9ozaz)
  • For context, I work on one-off research devices for which a cost of an op-amp isn't a problem. I'm not trying to economize the cost of one op-amp. I'm asking this question out of curiosity.
  • Once in a while in literature I see a DC offset subtraction loop.
  • ![instrumentation amplifier with a DC servo loop](https://electrical.codidact.com/uploads/ng4zzswvqxkoeigxwqoxd2jt61x2)
  • Here are a few more examples. [DC servo loop removes a DC offset after an op-amp.](https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/el.2014.2262) [DC servo loop removes DC current from a photodiode.](https://www.ti.com/lit/an/sboa324/sboa324.pdf)
  • What are the advantages of such DC offset removal loop, compared to an RC high-pass filter?
  • The RC filter would look like this.
  • ![instrumentation amplifier followed by an RC filter](https://electrical.codidact.com/uploads/6ahuncfpoqsph4lj468pubw9ozaz)
  • For context, I work on one-off research devices for which a cost of an op-amp isn't a problem. I'm not trying to economize the cost of one op-amp. I'm asking this question out of curiosity.
#2: Post edited by user avatar misk94555‭ · 2023-05-03T14:45:37Z (12 months ago)
  • Once in a while in literature I see a DC offset subtraction loop.
  • ![instrumentation amplifier with a DC servo loop](https://electrical.codidact.com/uploads/ng4zzswvqxkoeigxwqoxd2jt61x2)
  • Here's a [different example](https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/el.2014.2262) where a DC servo loop removes a DC offset.
  • What are the advantages of such DC offset removal loop, compared to an RC high-pass filter?
  • The RC filter would look like this.
  • ![instrumentation amplifier followed by an RC filter](https://electrical.codidact.com/uploads/6ahuncfpoqsph4lj468pubw9ozaz)
  • For context, I work on one-off research devices for which a cost of an op-amp isn't a problem. I'm not trying to economize the cost of one op-amp. I'm asking this question out of curiosity.
  • Once in a while in literature I see a DC offset subtraction loop.
  • ![instrumentation amplifier with a DC servo loop](https://electrical.codidact.com/uploads/ng4zzswvqxkoeigxwqoxd2jt61x2)
  • Here's [another example](https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/el.2014.2262) where a DC servo loop removes a DC offset after an op-amp.
  • What are the advantages of such DC offset removal loop, compared to an RC high-pass filter?
  • The RC filter would look like this.
  • ![instrumentation amplifier followed by an RC filter](https://electrical.codidact.com/uploads/6ahuncfpoqsph4lj468pubw9ozaz)
  • For context, I work on one-off research devices for which a cost of an op-amp isn't a problem. I'm not trying to economize the cost of one op-amp. I'm asking this question out of curiosity.
#1: Initial revision by user avatar misk94555‭ · 2023-05-03T00:14:05Z (12 months ago) 
DC offset correction loop (DC servo loop). What's its advantage, compared to a high-pass RC filter?
Once in a while in literature I see a DC offset subtraction loop.

![instrumentation amplifier with a DC servo loop](https://electrical.codidact.com/uploads/ng4zzswvqxkoeigxwqoxd2jt61x2)

Here's a [different example](https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/el.2014.2262) where a DC servo loop removes a DC offset.

What are the advantages of such DC offset removal loop, compared to an RC high-pass filter?  
The RC filter would look like this.

![instrumentation amplifier followed by an RC filter](https://electrical.codidact.com/uploads/6ahuncfpoqsph4lj468pubw9ozaz)

For context, I work on one-off research devices for which a cost of an op-amp isn't a problem. I'm not trying to economize the cost of one op-amp. I'm asking this question out of curiosity.
DC opamp integrator