Designing an RLC circuit from a given transfer function.

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SUMMARY

The discussion focuses on designing an RLC circuit based on a given transfer function derived from experimental data. The transfer function identified is H(ω)=0.064(1+j(ω/1660))/(1+j(ω/56)), with a Bode plot indicating a pole at 56Hz and a zero at 1660Hz. The objective is to create an inverse transfer function H(ω)=15.625(1+j(ω/56))/(1+j(ω/1660)) to cancel the effects of the original circuit. The design requires the use of an operational amplifier to achieve the necessary DC gain and to position the pole and zero correctly.

PREREQUISITES
  • Understanding of transfer functions in control systems
  • Familiarity with Bode plots and their interpretation
  • Knowledge of operational amplifier configurations
  • Basic circuit analysis involving resistors and capacitors
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  • Research operational amplifier circuit design for achieving specific gain values
  • Learn about designing filters to create desired poles and zeros in transfer functions
  • Study voltage divider circuits and their transfer functions
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Electrical engineers, circuit designers, and students studying control systems who are interested in practical applications of transfer functions and circuit design techniques.

MonsterAar
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Designing a circuit from a given transfer function.

I hope you don't mind that I haven't used the default format. It doesn't lend itself well to my problem.

The original problem is as follows:
We were given a 'black box' that contained a passive circuit and we experimentally determined a transfer function for the circuit by passing through various frequencies and recording the magnitude and phase of the outputs.

This was then used to create a bode plot. This bode plot showed a pole at approximately 56Hz and a zero at approximately 1660Hz. The DC gain of the circuit is 0.064.

From this information I deduced the transfer function of the circuit to be:
H(\omega)=0.064\frac{1+j\frac{\omega}{1660}}{1+j\frac{\omega}{56}}

The task now asks for us to design a circuit to cancel out the effects of the black box on the input signal. Basically we have to design a circuit so that when we have input-blackbox-our circuit-output, the input=output. So, I need to design a circuit with the inverse of the above transfer function.

IE. I need to design a circuit with the following transfer function:
H(\omega)=15.625\frac{1+j\frac{\omega}{56}}{1+j\frac{\omega}{1660}}

This is where I get stuck. How do I go about designing a circuit with a DC gain of 15.625, a pole at 1660Hz and a zero at 56Hz?
I understand I'll have to use an op-amp to get the DC gain greater than 1. Other than this I'm stuck.

Thanks,
Luke
 
Last edited:
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Consider a voltage divider composed of two resistors and a capacitor in series. The input voltage acts on all three components and the output voltage is taken on the series of the capacitor and one of the resistors.
What is the transfer function of this circuit?
 

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