How to Design a Circuit from a Given Transfer Function?

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Discussion Overview

The discussion revolves around designing a circuit based on a given transfer function, specifically T(s)=\frac{50000s}{(s+50)(s+1000)}. Participants explore methods to construct the circuit using operational amplifiers, resistors, capacitors, and inductors, with a focus on the implications of the transfer function in both time and frequency domains.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant expresses uncertainty about how to start designing a circuit from the transfer function and relates it to a time-domain representation.
  • Another participant suggests familiarizing oneself with transfer functions of simple RC filters and mentions the use of op-amps as buffers between filter stages.
  • A participant proposes separating the transfer function into two systems, H_{1}=\frac{50000}{s+50} and H_{2}=\frac{s}{s+1000}, and considers buffering them together.
  • There is a suggestion that interchanging the numerators could also be a viable approach.
  • A later reply indicates that one participant has successfully solved the problem, attributing their progress to the guidance received.

Areas of Agreement / Disagreement

While there is some agreement on the approach to take regarding the separation of the transfer function and the use of buffers, the discussion includes multiple perspectives on how to implement the circuit design, and it remains unresolved in terms of a definitive method.

Contextual Notes

Participants do not fully explore the implications of the specific component values or the exact configurations of the proposed circuit elements, leaving some assumptions and details unspecified.

Who May Find This Useful

Individuals interested in circuit design, particularly those working with transfer functions and operational amplifiers, may find this discussion relevant.

Lancelot59
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I'm given the following transfer function:
T(s)=\frac{50000s}{(s+50)(s+1000)}
and I need to constuct a circuit from it using opamps, resistors, capacitors, and inductors. Capacitors must be 100nF.

I'm not quite sure how to start here. I managed to get a time domain version of the transfer function:
T(t)=\frac{-50000}{19}e^{-50t}+\frac{100000}{19}e^{-1000t}

The problem is I have no idea how to get started. I know that the time function looks like a capacitor discharging, however I don't know how to start going about turning this function into a circuit.
 
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You should familiarize yourself with the transfer functions of the simple RC filters (low pass and high pass).

hint: An op-amp can be used as a buffer between filter stages (keeps them from interfering with each others corner frequencies and gains).
 
gneill said:
You should familiarize yourself with the transfer functions of the simple RC filters (low pass and high pass).

hint: An op-amp can be used as a buffer between filter stages (keeps them from interfering with each others corner frequencies and gains).

Ah, I see. So I can separate it into two systems with the following characteristics:

H_{1}=\frac{50000}{s+50} H_{2}=\frac{s}{s+1000}

and buffer them together?
 
Lancelot59 said:
Ah, I see. So I can separate it into two systems with the following characteristics:

H_{1}=\frac{50000}{s+50} H_{2}=\frac{s}{s+1000}

and buffer them together?

Yes, you could.
 
Or I could interchange the numerators. Either way this puts me on a better track, I'll see what I can come up with.
 
I managed to solve it! Thanks for pointing me in the right direction.
 

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