10.6 INVERSE HYBRID (OR g) PARAMETERS

If V ₁ and I ₂ are chosen as independent variables, the two-port network equations may be written as

In matrix form, these equations are written as

The constants g ₁₁, g ₁₂, g ₂₁, and g ₂₂ are known as inverse hybrid parameters or g-parameters. The g-parameters are defined as follows by using Equations (10.9) and (10.10).

If I ₂ = 0 the output port is open circuit.

open circuit input admittance.

open circuit forward voltage gain.

If

V ₁ = 0 the input port is short circuit.

short circuit reverse current gain.

short circuit output impedance.

From the definitions of the g-parameters, it is seen that g ₁₁ has the dimensions of admittance, g ₂₁ and g ₁₂ are dimensionless, and g ₂₂ has the dimensions of impedance.

By Equations (10.9) and (10.10), the equivalent circuit of a two-port network is as shown in the figure.

Figure 10.13: Equivalent circuit of a two-port network in terms of g-parameters

Example 10.6

Determine the Z- and g-parameters of the given network as shown in Figure 10.14

Solution: Two loop equations are

Figure 10.14

or

Comparing Equations (1) and (2) with the standard equation of the Z-parameters (10.1) and (10.2), we get

Now the standard equations of the g-parameters,

Rearranging Equation (1) into the form of Equation (10.9),

Putting the values of I ₁ from Equation (1a)...