# Electronic Devices and Circuits Questions and Answers – The High Frequency T Model

This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “The High Frequency T Model”.

1. What is the T represent in high frequency T model?
a) Transmission
b) Transistor
c) Tailgate
d) Thorough

Explanation: The T in high frequency T model represents transistor models. This demonstrates the study of high frequency input operations on multiple basic transistor models to observe the variation in the output characteristics.

2. Which model is similar to the high frequency T model?
a) G model
b) Hybrid-pi model
c) Inverse G model
d) Z model

Explanation: The Hybrid-pi model is similar to the high frequency T model. The T model can use either a voltage or a current as the variable that controls the current source. In the T model, the current source’s expression is either gm VBE or αIE.

3. How do we determine the hybrid parameters h11 and h21 in a high frequency T model?
a) Short circuiting the input terminal
b) Open circuiting the input terminal
c) Short circuiting the output terminal
d) Open circuiting the output terminal

Explanation: There are four h parameters, they are: h11, h12, h21 and h22. To determine the values of h11 and h21 we need to short circuit the output terminal of a given two-port network. Short circuiting the output terminal makes the output terminal voltage V2 equal to zero.

4. Which hybrid parameter is used to calculate forward current gain in a high frequency T model?
a) h11
b) h12
c) h21
d) h22

Explanation: The hybrid parameter h21 can be calculated by short circuiting the output port in a high frequency T model. By doing so, we can calculate h21 = I2 / I1. Since this is a ratio between two current units, h21 is unit less. It is known as the forward current gain of the circuit.

5. What is h11 also known as in a high frequency T model?
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 in a high frequency T model.
Sanfoundry Certification Contest of the Month is Live. 100+ Subjects. Participate Now!

6. How do we calculate the value of hybrid parameter h12 if V2 = 20V and V1 = 50V in a high frequency T model?
a) 0.04
b) 0.25
c) 0.4
d) 2.5

Explanation: To find the hybrid parameter h12 in a high frequency T model we use the below mentioned formula. Given values are V2 = 20V and V1 = 50V.
h21 = V1 / V2 = 50 / 20 = 2.5

7. How do we determine the hybrid parameters h12 and h22 in a high frequency T model?
a) Short circuiting the input terminal
b) Open circuiting the input terminal
c) Short circuiting the output terminal
d) Open circuiting the output terminal

Explanation: From the four hybrid parameters, to determine the value of h12 and h22 we need to open circuit the input terminal. This in turn makes the current from the input terminal I1 equal to zero. It is the same procedure in a high frequency T model.

8. Which of the following four hybrid parameters is used to calculate reverse voltage gain in a high frequency T model?
a) h11
b) h12
c) h21
d) h22

Explanation: The hybrid parameter h12 can be calculated by open circuiting the input port in a high frequency T model. By doing so, we can calculate h12 = V1 / V2. Since this is a ratio between two voltage units, h12 is unitless. It is known as the reverse voltage gain of the circuit.

9. In a high frequency T model, which parameter is known as the output conductance?
a) h11
b) h12
c) h21
d) h22

Explanation: When the input terminal of a two-port device is open circuited in a high frequency T model, the input current flowing equals to zero. Hence the value of h22 = I2 / V2. The unit of this parameter is ampere / volt or mho. Hence it is known as output conductance.

10. How do we determine the value of the hybrid parameter h21 in a high frequency T model?
a) h21 = I1 / I2
b) h21 = V1 / V2
c) h21 = I2 / I1
d) h21 = V2 / V1

Explanation: To calculate the value of h21 high frequency T model, we short circuit the output terminal so the output voltage V2 equals zero. Hence the equation for hybrid parameters becomes, I2 = h21I1 + 0. Therefore, h21 = I2 / I1.

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

To practice all areas of Electronic Devices and Circuits, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]