Transfer function from amplitude response?

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Discussion Overview

The discussion revolves around the process of deriving a transfer function from an amplitude response of a filter, specifically focusing on a method presented in an attached paper. The scope includes theoretical aspects of filter design and practical application using software tools like Mathematica.

Discussion Character

  • Technical explanation, Exploratory, Homework-related

Main Points Raised

  • One participant presents a method from a paper for generating a polynomial for the amplitude response of a filter, which is claimed to yield arbitrary flatness and roll-off characteristics.
  • The same participant expresses uncertainty about how to derive the transfer function from the given amplitude response, contrasting it with standard filters like Butterworth or Chebyshev.
  • Another participant claims to have figured out the process and offers to share a Mathematica notebook that accomplishes this task.
  • A subsequent reply expresses interest in obtaining the Mathematica notebook for experimentation.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the method for deriving the transfer function from the amplitude response, as one participant is seeking clarification while another claims to have found a solution.

Contextual Notes

The discussion lacks detailed steps or assumptions regarding the derivation process, and the specific conditions under which the proposed method is applicable remain unclear.

cuallito
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Hi, in the paper I've attached, they give a method for generating a polynomial g for the amplitude response of a filter that gives arbitrary flatness and roll-off characteristics.

\frac{1}{\sqrt{1+g}}

And then they say the transfer function can be easily determined from this, but they don't say how.

For example, they give an amplitude response

\frac{1}{\sqrt{1+10s^{8}-24w^{10}+15w^{12}}}

and then they just say "then we will have the transfer function"

\frac{0.259}{s^{6}+2.392w^{5}+3.661s^{4}+2.755s^{3}+2.615s^{2}+1.162s+0.259}

I know how to get the transfer function from the amplitude response for a standard filter like a butterworth or chebyshev, but for ones like this?
 

Attachments

Engineering news on Phys.org
Hey, I figured it out. I wrote a Mathematica note book that does it. Anyone want it?
 
cuallito said:
Hey, I figured it out. I wrote a Mathematica note book that does it. Anyone want it?

Cool. Yes please, it would be fun to try out. Can you post it as an attachment?
 
Yeah.
 

Attachments

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