H Parameters (Hybrid Parameters) in Two Port Networks

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H-PARAMETER OF TWO PORT NETWORK
H-PARAMETER OF TWO PORT NETWORK

H Parameters (Hybrid Parameters) in Two Port Networks

Hello friends, in this article we will study about h-Parameter of two port network.
h-Parameter representation is widely used in modelling of electronic components and circuits, particularly transistors.
h-Parameter is called “Hybrid Parameter”.

In h-Parameter, the input voltage and output current are function of input current and output voltage respectively.
( V1 , I2 )      =        f ( I1 , V2 )

In matrix form,
[V1] =    [h11  h12]   [I1]
[I2] =     [h21  h22]   [V2]

Writing it in equation,
V1 = h11* I1 + h12* V2 ………eq1
I2 =  h21* I1 + h22* V2 ………eq2

CASE-1 SHORT CIRCUITING THE OUTPUT PORT.

If the Output port of the two port network is  short circuited then output voltage is zero, i.e. V2 = 0.

H parameter

Now, equation 1 and 2 will be reduced to :

V1 = h11* I1
I2 =  h21* I1

So, h11 = V1 /I1    ( keeping V2 = 0 )

h21 = I2/ I1    ( keeping V2 = 0 )

CASE-2 OPEN CIRCUITING THE INPUT PORT.

If the Input port of the two port network is open circuted then the input current is zero, i.e. I1 = 0.

H parameter

Now, equation 1 and 2 will be reduced to :
V1 = h12* V2
I2 =  h22* V2

So, h12 = V1/ V2    ( keeping I1= 0 )

h22 = I2/ V2   ( keeping  I1 = 0 )

h11 is called input impedance and its unit is ohm.
h12 is called forward current gain and is unitless.
h21 is called reverse voltage and is unitless.
h22 is called output impedance and its unit is mho.


For a network to be symmetrical,
h11*h22 – h12*h21 = 0. (∆h=0)

For a network to be reciprocal,  h12 = -h21

EQUIVALENT CIRCUIT OF Y-PARAMETER

Equivalent circuit of H parameter

 

READ HERE  Nilpotent matrix - properties and example

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