Question 17.6: The h-parameters of a two-port network are h11 = 2kΩ, h12 = ......
The h-parameters of a two-port network are h_{11} = 2kΩ, h_{12} = –2, h_{21} = 10, and h_{22} = 500 μS. A 10-V voltage source is connected at the input port. Find the Norton equivalent circuit at the output port.
The given h-parameters give the i-ν relationships of the two port as
V_{1} = 2000I_{1} – 2V_{2}
I_{2} = 10I_{1} + 5 × 10^{-4}V_{2}
The voltage source connected at the input port makes V_{1} = 10 V. Inserting this value into the first h-parameter equation and solving for I_{1} yields
I_{1} = \frac{1}{200}+ \frac{1}{1000}V_{2}
Substituting this into the second h-parameter equation produces
I_{2} = \frac{1}{20}+\left(\frac{ 1}{100}+ 5 × 10^{-4}\right)V_{2}
This equation gives the actual i-v relationship at the output port with the 10-V source connected at the input. Figure 17–7 shows the desired Norton equivalent circuit.
Summing the currents at node A yields the i-ν relationship of the desired Norton circuit as
I_{2} = -I_{N} + G_{N}V_{2}
Comparing the Norton and the actual characteristics we conclude that
I_{N} = -\frac{1}{20}= -50 mA
G_{N} = \frac{1}{100}+5 × 10^{-4} = 10.5 mS
