**y Parameters of Two Port Network:**

y Parameters of Two Port Network are also called admittance parameters. These are obtained by expressing currents at two ports in terms of voltages at two ports. Thus, voltages V_{1} and V_{2} are independent variables, while I_{1} and I_{2} are dependent variables. Thus, we have

In equation form, above relations can be written as,

In matrix form, above equations can be written as,

The individual y-parameters are defined as follows.

This is called **driving point input admittance**.

This is called **forward transfer admittance**.

This is called **reverse transfer admittance**

This is called **output admittance**.

These parameters are defined individually only when the voltage in any one of the ports is zero. This corresponds to the condition that one of the ports is short circuited. Hence y-parameters are also called **short circuit admittance parameters**.

The equivalent circuit of a y Parameters of Two Port Network interms of short circuit admittance parameters satisfying equations (1) and (2) is as shown in the Fig. 6.4.