How to Derive and Sketch the Frequency Response Function in an RC Circuit?

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SUMMARY

The frequency response function G(iw) for an RC circuit is defined as G(iw) = iwCR / (1 + iwCR). This relationship is derived using voltage division from the input voltage V(t) and the output voltage across the resistor VR(t). The discussion also emphasizes the importance of separating the real and imaginary components of G(iw) to sketch its locus on the Argand diagram. The approach involves applying the Laplace transform and substituting s = jw to analyze the steady-state solution.

PREREQUISITES
  • Understanding of RC circuit theory
  • Familiarity with Laplace transforms
  • Knowledge of complex numbers and Argand diagrams
  • Experience with voltage division in electrical circuits
NEXT STEPS
  • Study the application of Laplace transforms in circuit analysis
  • Learn about the derivation of frequency response functions in different circuit configurations
  • Explore the sketching of loci for complex functions on Argand diagrams
  • Investigate the implications of frequency response in signal processing
USEFUL FOR

Electrical engineering students, circuit designers, and anyone involved in analyzing the frequency response of RC circuits.

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Homework Statement


The relationship between the input voltage V(t) and the output voltage across a resistor VR(t) is:-

CR dVR /dt + VR = CR dV/dt

Circuit diagram of a capacitor and resistor with VR(t) in series across V(t)

1. Show that the frequency response function G(iw) (w= omega) is given by G (iw) = iwCR/ (1 + iwCR)

2.Sketch the locus of the frequency response function, G(iw) (w= omega) on the argand diagram.

Homework Equations



CR dVR /dt + VR = CR dV/dt

G (iw) = iwCR/ (1 + iwCR)

The Attempt at a Solution



1. I got this G (iw) = iwCR/ (1 + iwCR) by voltage division, from the circuit, but how could I do that from the given equation?

2. By taking the real and imaginary parts; G(iw) = x + iy

x = (wcr)2 /(1 + (wcr)2)
y = wcr/ ( 1 + (wcr)2)

G(iw) = (wcr)2 /(1 + (wcr)2) + iwcr/ ( 1 + (wcr)2)

I'm having trouble eliminating wcr now...:frown:
 
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I thought you'd apply Laplace transform and then subst s= jw to get the steady state solution. Then proceed to find the frequency response. But you arrived at the answer in one step, so why are you simplifying it further?
 

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