**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__.

__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.

#### 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.__

__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.

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**