# Electronic Devices and Circuits Questions and Answers – Hybrid PI Conductances in Low Frequency H Parameters

This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Hybrid PI Conductances in Low Frequency H Parameters”.

1. For the two-port network shown below, assume R1 = R2 = 10kΩ. What is the value of the hybrid-pi conductance in low frequency H-parameters h22 ?

a) 0.1 mho
b) 10 mhos
c) 20 mhos
d) 15 mhos

Explanation: To calculate h22, we open circuit the input terminal. Hence the current flowing through resistor R1 is zero and the voltage V1 across the input terminal is equal to the voltage V2 across output terminal. Therefore, to find h22, given that R2 = 10kΩ.
V1 = V2
I2 = V2 / 10 kΩ
h22 = I2 / V2 = 0.1 mho

2. For the two-port network shown below, assume R1 = R2 = 10kΩ. What is the value of the hybrid-pi in low frequency H-parameters h11 ?

a) 10kΩ
b) 20kΩ
c) 10kΩ
d) 5kΩ

Explanation: To calculate h11, we short circuit the output terminal. Hence the current flowing through resistor R2 is zero. Therefore, to find h11, given that R1 = 10kΩ.
V1 = R1 x I1 (According to Ohm’s law)
h11 = V1 / I1 = R1 x I1 / I1 = R1 = 10kΩ.

3. How do we calculate the inverse hybrid-pi in low frequency H-parameters g11 of a two-port network?
a) g11 = I1 / V1
b) g11 = I2 / V1
c) g11 = I1 / V2
d) g11 = I2 / V2

Explanation: The inverse hybrid-pi conductance in low frequency H-parameters g11 for a two-port network is calculated by open circuiting the output terminal. In this case, the current I2 is equal to zero. The parameter g11 is calculated by taking the ratio of input terminal current over input terminal voltage.

4. What are the hybrid-pi conductance in low frequency H-parameters used to analyze?
a) MOSFET
b) Junction Field Effect Transistor
c) Bipolar Junction Transistor
d) It has no use

Explanation: The four hybrid-pi conductance in low frequency H-parameters of a two-port network are used to analyze the workings of a Bipolar Junction Transistor or in other words a BJT. The inverse hybrid-pi conductance in low frequency H-parameters are used to analyze the Junction Field Effect Transistor of JFET.

5. How is the h21 hybrid-pi conductance in low frequency H-parameters of a two-port network used?
a) It is used as a voltage source at input port
b) It is used as a current source at input port
c) It is used as a voltage source at output port
d) It is used as a current source at output port

Explanation: While checking the hybrid-pi conductance in low frequency H-parameters equivalent network of a two-port network we see that the hybrid-pi conductance in low frequency H-parameters h21 is sued as a current source at the output port. While using Kirchhoff’s current law, the hybrid-pi conductance in low frequency H-parameters equations can be represented as a current source of h21 I1 .

6. How do we calculate the inverse hybrid-pi conductance in low frequency H-parameters g21 of a two-port network?
a) g21 = I1 / I2
b) g21 = I2 / I1
c) g21 = V2 / V1
d) g21 = V1 / V2

Explanation: The inverse hybrid-pi conductance in low frequency H-parameters g21 for a two-port network is calculated by open circuiting the output terminal. In this case, the current I2 is equal to zero. The parameter g21 is calculated by taking the ratio of output terminal voltage over input terminal voltage. It is also known as the open circuit voltage gain.

7. How is the h12 hybrid-pi conductance in low frequency H-parameters of a two-port network used?
a) It is used as a voltage source at output port
b) It is used as a current source at output port
c) It is used as a voltage source at input port
d) It is used as a current source at input port

Explanation: While checking the hybrid-pi conductance in low frequency H-parameters equivalent network of a two-port network we see that the hybrid-pi conductance in low frequency H-parameters h12 is sued as a voltage source at the input port. While using Kirchhoff’s voltage law, the hybrid-pi conductance in low frequency H-parameters equations can be represented as a fixed voltage source of h21 V2 .

8. How do we calculate the inverse hybrid-pi conductance in low frequency H-parameters g12 of a two-port network?
a) g12 = I2 / I1
b) g12 = I1 / I2
c) g12 = V1 / V2
d) g12 = V2 / V1

Explanation: The inverse hybrid-pi conductance in low frequency H-parameters g12 for a two-port network is calculated by short circuiting the input terminal. In this case, the current V1 is equal to zero. The parameter g12 is calculated by taking the ratio of input terminal current over output terminal current.

9. How do we calculate the inverse hybrid-pi conductance in low frequency H-parameters g22 of a two-port network?
a) g22 = V2 / I1
b) g22 = I1 / V2
c) g22 = V1 / I2
d) g22 = V2 / I2

Explanation: The inverse hybrid-pi conductance in low frequency H-parameters g22 for a two-port network is calculated by short circuiting the output terminal. In this case, the current V1 is equal to zero. The parameter g22 is calculated by taking the ratio of output terminal voltage over output terminal current.

10. We can measure hybrid h-parameters using inverse hybrid g-parameters.
a) True
b) False

Explanation: The hybrid h-parameters can be measured using the inverse hybrid g-parameters. All the parameters used to analyze a two-port network can be used to convert and measure other different parameters.

11. What is h11 also known as in hybrid-pi conductance in low frequency H-parameters?
a) Input conductance
b) Input resistance
c) Output conductance
d) Output resistance

Explanation: The parameter h11 can be calculated by short circuiting the output port. By doing so, we can calculate h11 = V1 / I1 . Since this gives h11 the units of volts/ampere or in other words ohms, it is also known as input resistance.

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