The Jacob Shekel circuit analysis method - Need help from The Electrician!

Discussion in 'General Electronics Chat' started by bitrex, Oct 24, 2010.

  1. bitrex

    Thread Starter Member

    Dec 13, 2009
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    I was reviewing the method of circuit analysis that The Electrician sent me some files about a while back, using admittance matricies. Unfortunately, I'm somewhat confused about how the admittance matricies for the transistors in a circuit were developed - if The Electrician is around, could you walk me through how the matricies for the transistors were derived in the following: http://forum.allaboutcircuits.com/attachment.php?attachmentid=11648&d=1250840496

    I have a PDF specifically on the topic that you sent me, but unfortunately some of the figures in it are hard to read from the scan and I'm having a difficult time translating the matricies given in the document into the ones you derived, regardless.

    Thanks in advance.
     
  2. Jony130

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    Feb 17, 2009
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  3. bitrex

    Thread Starter Member

    Dec 13, 2009
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    Thanks for the reply, though I'm not sure that the transformation matrix is what I need. I'm wondering how to relate an indefinite admittance matrix such as the one at the top left of this link:

    http://forum.allaboutcircuits.com/attachment.php?attachmentid=11648&d=1250840496


    To the various transistor parameters. Essentially I'm trying to figure out why the values in the matrix are what they are.
     
  4. Jony130

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    Feb 17, 2009
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    Well, here you have matrix for CE amplifier

    Y = \left[ \begin{array}{2}\frac{1}{h11} & \frac{-h12}{h11}\\  \frac{h21}{h11} &  \frac{h11*h22-h12*h21}{h11}\end{array}\right]

    And
    H11 = (β+1)*re
    H21 = β
    H22 = ro
    H12 = ?? I don't know

    And if emitter in not grounded the re need to be add.

    So
    1/H11 = 1/(β+1)*re

    H21/H11 = β/(β+1)*re
    And so on.
     
  5. The Electrician

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    Oct 9, 2007
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    Here's some explanation of how to deal with transistors.

    Let me know if you need more.
     
    bitrex likes this.
  6. bitrex

    Thread Starter Member

    Dec 13, 2009
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    Thank you! To use this method it looks like I need to know the h parameters of a transistor in its various configurations - common emitter, common base, etc. Is there somewhere I can find such a list?
     
  7. The Electrician

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    Oct 9, 2007
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    You can just do what I mentioned in the first image above, where I say:

    "Now that we have an indefinite matrix, we can get the definite matrix for the circuit with a different node grounded. Just delete the row and column corresponding to the node to be grounded"

    So, you can start with, for example, the definite matrix of a common emitter configuration, convert it to an indefinite matrix and then delete the node corresponding to the base and you will have a 2x2 definite matrix for a common base configuration.
     
  8. bitrex

    Thread Starter Member

    Dec 13, 2009
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    Great! I'm going to start practicing with this method, using Maxima for the matrix manipulations.
     
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