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

AI Thread Summary
The discussion focuses on deriving the frequency response function G(iw) for an RC circuit, resulting in G(iw) = iwCR / (1 + iwCR) through voltage division. Participants explore how to simplify and sketch the function on an Argand diagram, breaking it into real and imaginary components. There is confusion regarding the elimination of the term wCR and the application of Laplace transforms for steady-state solutions. The conversation highlights the importance of understanding both the derivation and the graphical representation of the frequency response. Overall, the thread emphasizes the analytical approach to solving circuit response problems.
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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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