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

#### bitrex

Joined Dec 13, 2009
79
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.

#### bitrex

Joined Dec 13, 2009
79
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:

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

#### Jony130

Joined Feb 17, 2009
5,186
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.

#### The Electrician

Joined Oct 9, 2007
2,803
Here's some explanation of how to deal with transistors.

Let me know if you need more.

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#### bitrex

Joined Dec 13, 2009
79
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?

#### The Electrician

Joined Oct 9, 2007
2,803
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?
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.