How to Design a Circuit from a Given Transfer Function?

In summary, the conversation discusses constructing a circuit using opamps, resistors, capacitors, and inductors from a given transfer function. The time domain version of the transfer function is also provided. The expert suggests familiarizing oneself with simple RC filters and using an op-amp as a buffer between filter stages. It is also suggested to separate the transfer function into two systems and buffer them together. The person is able to solve the problem with the help of the expert's guidance.
  • #1
Lancelot59
646
1
I'm given the following transfer function:
[tex]T(s)=\frac{50000s}{(s+50)(s+1000)}[/tex]
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:
[tex]T(t)=\frac{-50000}{19}e^{-50t}+\frac{100000}{19}e^{-1000t}[/tex]

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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  • #2
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).
 
  • #3
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:

[tex]H_{1}=\frac{50000}{s+50} H_{2}=\frac{s}{s+1000}[/tex]

and buffer them together?
 
  • #4
Lancelot59 said:
Ah, I see. So I can separate it into two systems with the following characteristics:

[tex]H_{1}=\frac{50000}{s+50} H_{2}=\frac{s}{s+1000}[/tex]

and buffer them together?

Yes, you could.
 
  • #5
Or I could interchange the numerators. Either way this puts me on a better track, I'll see what I can come up with.
 
  • #6
I managed to solve it! Thanks for pointing me in the right direction.
 

FAQ: How to Design a Circuit from a Given Transfer Function?

1. How do you determine the transfer function of a circuit?

The transfer function of a circuit can be determined by taking the Laplace transform of the circuit's input and output signals and then taking the ratio of the two. This will give you the transfer function in terms of the Laplace variable s.

2. What is the significance of the transfer function in a circuit?

The transfer function represents the relationship between the input and output signals of a circuit in the frequency domain. It provides information about the frequency response and stability of the circuit.

3. Can a circuit have multiple transfer functions?

Yes, a circuit can have multiple transfer functions depending on the number of inputs and outputs. Each input-output pair will have its own unique transfer function.

4. How is the transfer function used in circuit analysis?

The transfer function is used in circuit analysis to determine the frequency response of a circuit and to design filters and control systems. It can also be used to evaluate the stability of a circuit.

5. Can you convert a transfer function back to a circuit?

Yes, a transfer function can be converted back to a circuit by using inverse Laplace transforms. However, the resulting circuit may not be identical to the original as there are multiple circuits that can have the same transfer function.

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