Finding the transfer function for a parallel resonant circuit

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SUMMARY

The discussion focuses on deriving the transfer function for a parallel RLC filter, specifically using the equation H(w) = ZLC / Ztot. The user has calculated the impedance ZLC as [(+jwL)(-j/wC)] / (jwL) + (-j/wC) and the total impedance Ztot as ZLC + R. The user is struggling with simplifying the complex numbers in the equation and proving the equivalence to the bandpass filter equation H(f) = 1/ (1 + j*Qp* (f/f0 - f0/f)). Key parameters include a bandwidth of 20,000 Hz, a resonant frequency of 980,000 Hz, and a quality factor Qp of 49.

PREREQUISITES
  • Understanding of complex impedance in RLC circuits
  • Familiarity with transfer functions in control systems
  • Knowledge of bandpass filter characteristics
  • Proficiency in manipulating complex numbers and phasors
NEXT STEPS
  • Study the derivation of transfer functions for RLC circuits
  • Learn about complex number simplification techniques
  • Research the characteristics of bandpass filters and their equations
  • Explore the implications of the quality factor Qp in filter design
USEFUL FOR

Electrical engineers, students studying circuit theory, and anyone involved in filter design and analysis will benefit from this discussion.

Krom1985
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Homework Statement


Hello, so I'm trying to solve the transfer function for a parallel RLC filter that goes like

-------Resistor -------------------
|XXXXXXXXXXXXXXXXX|XXXX|
|XXXXXXXXXXXXXXXXX|XXXX|
VinXXXXXXXXXXXXXXXXCXXXXL
|XXXXXXXXXXXXXXXXX|XXXX|
|XXXXXXXXXXXXXXXXX|XXXX|
|---------------------------------
the Xs are just empty space, multiple space bars wouldn't show up correctly
so I'm given the equation for the transfer function which is
I just realized that the problem actually had 2 parts.
First, the equation to use to solve transfer function is:

H(w) = ZLC / Ztot
I found ZLC to be [(+jwL)(-j/wC)] / (jwL) + (-j/wC)
and Z total to be {[(+jwL)(-j/wC)] / (jwL) + (-j/wC)} + R
I'm having trouble getting rid of the js in the equation and solving it.
I keep trying to do basic math operations and js just keep stacking up like j^2 and j^3.. I'm pretty sure they're not even supposed to be treated as normal variables.Also, the second part which may be a little easier is to take the above equation and rearranging it and prove that the above equation is equal to the equation below. I'm stuck on this one as well since I haven't solved the first part.

H(f) = 1/ (1 + j*Qp* (f/f0 - f0/f))

So this is a bandpass filter, and the bandwidth is 20000 Hz, and resonant frequency is 980000 Hz and I've found the quality factor to be 49 by taking Qp = f0 / B
 
Last edited:
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Just edited to make the problem actually solvable. Can somebody help me?
 

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