Hybrid parameters (or) h - parameters:-

• If the input current that is denoted as i₁ and output Voltage that is denoted as V₂ are takes as independent variables, input voltage V₁ and the output current i₂ can be written as shown below:

            V₁ = h₁₁ i₁ + h₁₂ V₂

             i₂  =  h₂₁ i₁ + h₂₂ V₂

The four hybrid parameters that are h₁₁, h₁₂, h₂₁ and h₂₂ are defined like this

            h₁₁ = [V₁ / i₁] with V₂ = 0        

= Input Impedance along with output part short circuited.

            h₂₂ = [i₂ / V₂] with i₁ = 0

 = Output admittance along with input part open circuited.

            h₁₂ = [V₁ / V₂] with i₁ = 0

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

            h₂₁ = [i₂ / i₁] with V₂ = 0

 = Forward current gain along with output part short circuited.

The dimensions of h - parameters are like this:

h₁₁ - ?

h₂₂ - 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.