two port network

 A pair of terminals is called a PORT.

at this stage we will be studying only two port network.  A port has the property that in one of the terminal the current enters and it exits from the other.


in two port networks we have four quantities to track of [[[[[[[[[V1,V2,I1,I2  ]]]]]]]]]]]

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______________________in these only two are independent _________________________


IMPEDANCE PARAMETERS::::::::::::::::::::::::::::::
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They play a vital role in synthesis of filters and also widely used in the design and analysis of impedance matching networks and power distribution networks.

V1=I1*z11+I2*z12
V2=I2*Z22+ I1*Z21

equating one to zero and then evaluating will give the others.



ADMITTANCE PARAMETERS:::::::::::::::::::::::::::::::::
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In certain of cases impedance parameters may not exist at all. And for those cases we have admittance parameters which will do with V1 and V2 in terms of I1 and I2.

I1= V1*y11+ V2*y12
I2=V2*y22+V1*y21


HYBRID PARAMETERS::::::::::::::::::::::::::::::::::::::::::::
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V1=h11*I1+h12*V2
I2=h21*I1+h22*V2

concept of symmetricallicty

conversion to T network  and if not the general equivalent ::::::::::::::::::

       z11-z12                       z22-z12                                             z11*I1                                     z22*I2
                              z12                                                                                z12*I2      z21*I1

An ideal transformer has no Z--parameters

                     so::::::::::::                       V1         I1
                                                        __   ==  __ == n^-1
                                                       V2          I2

transformer is an example of two port network
transistor can also be modelled as two port network

Basically two separate ports for input and output ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::


common ground two port network ____________________________________________________

INTERCONNECTED TWO PORT NETWORKS :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

A> parallel    --- Y= Ya + Yb

B> Series  --- Z=Za + Zb

C> cascade  T = Ta* Tb