**Hybrid parameters (or) h - parameters:-**

- If the input current that is denoted as i
_{1} and output Voltage that is denoted as V_{2} are takes as independent variables, input voltage V_{1} and the output current i_{2} can be written as shown below:

V_{1} = h_{11} i_{1} + h_{12} V_{2}

i_{2} = h_{21} i_{1} + h_{22} V_{2}

The four hybrid parameters that are h_{11}, h_{12}, h_{21} and h_{22} are defined like this

h_{11} = [V_{1} / i_{1}] with V_{2} = 0

= Input Impedance along with output part short circuited.

h_{22} = [i_{2} / V_{2}] with i_{1} = 0

= Output admittance along with input part open circuited.

h_{12} = [V_{1} / V_{2}] with i_{1} = 0

= reverse voltage transfer ratio along with input part open circuited.

h_{21} = [i_{2} / i_{1}] with V_{2} = 0

= Forward current gain along with output part short circuited.

The dimensions of h - parameters are like this:

h_{11} - ?

h_{22} - mhos

h12, h21 - dimension less.

- Since the dimensions are not alike, that is they are hybrid in nature, and these parameters are termed as hybrid parameters.

I = 11 = input ; 0 = 22 = output ;

F = 21 = forward transfer ; r = 12 = Reverse transfer.