Network functions

Discussion in 'Homework Help' started by smock, Jan 29, 2011.

  1. smock

    Thread Starter New Member

    Jan 29, 2011
    5
    0
    Hello,

    While practicing problems in preparation for my midterm next week, I came across the following question.

    The network shown below (please see attachment) has poles at -1.5+((√111)/2) and -1.5-((√111)/2), and a zero at -3.

    In addition, it is known that the impedance at zero frequency (s=0 or direct current) is 1 ohm, that is Z(0) = 1. Determine the values of R, L, C in the network.

    I was easily able to determine the value of R by just getting Zeq and setting s = 0 to 1.
    However, I don't know how to find the values of L and C. any help that can be rendered is much appreciated.

    Thanks.
     
  2. Georacer

    Moderator

    Nov 25, 2009
    5,142
    1,266
    I don't have much experience with RLC networks, but the theory is this:

    You construct the transfer function of the circuit and you convert it to its Laplace transformation. I suggest viewing the R,L and C components as "blocks" that are to be merged serially or parallely. This TF is a function of R, L and C.

    You substitute R with the value you found. Afterwards, you calculate the poles and zeroes from the TF and you equate them with the ones given to get a system of 2 equations with 2 unknowns.
     
    Last edited: Jan 29, 2011
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