**Y-PARAMETER of Two Port Network**

#### Hello friends, in this article we will study about Y Parameter of two port network.

Y-Parameter is also called “Short Circuit Parameter” and “Admittance Parameter”.

In Y-Parameter, the input and output currents are function of input and output Voltages.

**( I1 , I2 ) = f ( V1 , V2 )**

It can also be written as:

**[I] = [Y] [V]**

where [Y] represents Admittance Matrix.

In matrix form,

**[I1] = [Y11 Y12] [V1]**

**[I2] = [Y21 Y22] [V2]**

Writing it in equation,

I1 = Y11* V1 + Y12* V2 ………eq1

I2 = Y21* V1 + Y22* 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 :

I1 = Y11* V1

I2 = Y21* V1

So, **Y11 = I1 /V1 **( keeping V2 = 0 )

** Y21 = I2/ V1 **( keeping V2 = 0 )

__CASE-2 SHORT CIRCUITING THE INPUT PORT.__

__CASE-2 SHORT CIRCUITING THE INPUT PORT.__

#### If the Input port of the two port network is short circuited then the input voltage is zero, i.e. V1 = 0.

#### Now, equation 1 and 2 will be reduced to :

I1 = Y12* V2

I2 = Y22* V2

So, **Y12 = I1/ V2** ( keeping V1= 0 )

** Y22 = I2/ V2** ( keeping V1 = 0 )

*Y11 is called input driving point Admittance.*

*Y12 is called forward transfer Admittance.*

*Y21 is called reverse transfer Admittance*

*Y22 is called output driving point Admittance.*

For a network to be symmetrical , **Y11 = Y22**

For a network to be reciprocal, **Y12 = Y21**