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 R_{1} = R_{2} = 10kΩ. What is the value of the hybrid-pi conductance in low frequency H-parameters h_{22} ?

a) 0.1 mho

b) 10 mhos

c) 20 mhos

d) 15 mhos

View Answer

Explanation: To calculate h

_{22}, we open circuit the input terminal. Hence the current flowing through resistor R

_{1}is zero and the voltage V

_{1}across the input terminal is equal to the voltage V

_{2}across output terminal. Therefore, to find h

_{22}, given that R

_{2}= 10kΩ.

V

_{1}= V

_{2}

I

_{2}= V

_{2}/ 10 kΩ

h

_{22}= I

_{2}/ V

_{2}= 0.1 mho

2. For the two-port network shown below, assume R_{1} = R_{2} = 10kΩ. What is the value of the hybrid-pi in low frequency H-parameters h_{11} ?

a) 10kΩ

b) 20kΩ

c) 10kΩ

d) 5kΩ

View Answer

Explanation: To calculate h

_{11}, we short circuit the output terminal. Hence the current flowing through resistor R

_{2}is zero. Therefore, to find h

_{11}, given that R

_{1}= 10kΩ.

V

_{1}= R

_{1}x I

_{1}(According to Ohm’s law)

h

_{11}= V

_{1}/ I

_{1}= R

_{1}x I

_{1}/ I

_{1}= R

_{1}= 10kΩ.

3. How do we calculate the inverse hybrid-pi in low frequency H-parameters g_{11} of a two-port network?

a) g_{11} = I_{1} / V_{1}

b) g_{11} = I_{2} / V_{1}

c) g_{11} = I_{1} / V_{2}

d) g_{11} = I_{2} / V_{2}

View Answer

Explanation: The inverse hybrid-pi conductance in low frequency H-parameters g

_{11}for a two-port network is calculated by open circuiting the output terminal. In this case, the current I

_{2}is equal to zero. The parameter g

_{11}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

View Answer

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 h_{21} 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

View Answer

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 h

_{21}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 h

_{21}I

_{1}.

6. How do we calculate the inverse hybrid-pi conductance in low frequency H-parameters g_{21} of a two-port network?

a) g_{21} = I_{1} / I_{2}

b) g_{21} = I_{2} / I_{1}

c) g_{21} = V_{2} / V_{1}

d) g_{21} = V_{1} / V_{2}

View Answer

Explanation: The inverse hybrid-pi conductance in low frequency H-parameters g

_{21}for a two-port network is calculated by open circuiting the output terminal. In this case, the current I

_{2}is equal to zero. The parameter g

_{21}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 h_{12} 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

View Answer

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 h

_{12}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 h

_{21}V

_{2}.

8. How do we calculate the inverse hybrid-pi conductance in low frequency H-parameters g_{12} of a two-port network?

a) g_{12} = I_{2} / I_{1}

b) g_{12} = I_{1} / I_{2}

c) g_{12} = V_{1} / V_{2}

d) g_{12} = V_{2} / V_{1}

View Answer

Explanation: The inverse hybrid-pi conductance in low frequency H-parameters g

_{12}for a two-port network is calculated by short circuiting the input terminal. In this case, the current V

_{1}is equal to zero. The parameter g

_{12}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 g_{22} of a two-port network?

a) g_{22} = V_{2} / I_{1}

b) g_{22} = I_{1} / V_{2}

c) g_{22} = V_{1} / I_{2}

d) g_{22} = V_{2} / I_{2}

View Answer

Explanation: The inverse hybrid-pi conductance in low frequency H-parameters g

_{22}for a two-port network is calculated by short circuiting the output terminal. In this case, the current V

_{1}is equal to zero. The parameter g

_{22}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

View Answer

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 h_{11} also known as in hybrid-pi conductance in low frequency H-parameters?

a) Input conductance

b) Input resistance

c) Output conductance

d) Output resistance

View Answer

Explanation: The parameter h

_{11}can be calculated by short circuiting the output port. By doing so, we can calculate h

_{11}= V

_{1}/ I

_{1}. Since this gives h

_{11}the units of volts/ampere or in other words ohms, it is also known as input resistance.

**Sanfoundry Global Education & Learning Series – Electronic Devices and Circuits.**

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