Important Two marks Questions with Answers on Multistage Amplifiers and Differential Amplifier

TWO MARKS QUESTION AND ANSWERS

1. Define multistage amplifier.

Multistage amplifier is defined as an amplifier in which more than one amplifying stage is used to achieve greater voltage and power gain.

2. Mention the types of multistage amplifiers.

i. Cascade Amplifier

ii. Cascode Amplifier

3. What do you mean by Cascade amplifier?

The output of one stage is fed as the input of the next stage. Two or more CE amplifier are connected together to form cascade amplifier.

4. What is Cascade amplifier?

It is the combination of CE and CB amplifiers. The output of CE amplifier is connected as the input of CB amplifier.

5. Define voltage gain of a multistage amplifier.

The voltage gain is defined as the product of the gain of the individual stages of the multistage amplifier.

A_V = A_V1 A_V2 ... A_Vn

6. What are the basic requirements of multistage amplifier?

i. Impedance matching

ii. High gain

iii. Large bandwidth

7. What is BIMOS amplifier?

The common gate (CG) amplifier stage is connected in cascade with a common source (CS) amplifier to form a BIMOS amplifier.

8. Define differential amplifier.

The differential amplifier is defined as the amplifier which amplifies the difference between two input signals.

V_O = V₁ - V₂

9. What do you mean by common mode signal?

The signal which is common to both input terminals is called common mode signal.

10. What do you mean by differential mode signal?

When the two applied signals are different, the output is the difference between two input signals. The output difference signal is called differential mode signal.

11. Define differential gain.

Differential gain is defined as the gain with which the differential amplifier amplifies the differential signal.

12. Define common mode gain.

Common mode gain is defined as the gain with which a practical differential amplifier amplifies the common mode signal.

13. Define CMRR.

Common Mode Rejection Ratio (CMRR) is defined as the ability of a differential amplifier to reject the common mode signal. It is the figure of merit of a differential amplifier.

14. Write the features of differential amplifier.

i. High differential gain

ii. Low common mode gain

iii. High CMRR

iv. High input impedance and low output impedance

v. High gain

vi. Large Bandwidth

15. Define differential input impedance.

The differential input impedance is defined as the equivalent resistance between one of the input to the ground terminal when the other terminal is connected to ground.

16. What are the types of differential amplifier?

i. Dual input Balanced Output Amplifier

ii. Dual input Unbalanced Output Amplifier

iii. Single input Balanced Output Amplifier

4. Single input Unbalanced Output Amplifier

17. How can CMRR be improved?

i. Increase differential gain Ad

ii. Decrease common mode gain Ac

18. Write the features of FET differential amplifier.

i. Very high input impedance

ii. Low differential gain

iii. Low input bias and offset current

iv. More noise

19. Define tuned amplifier?

An amplifier which amplifies specific frequency is called tuned amplifier.

20. How tuned amplifiers are classified?

i. Small signal tuned amplifiers

ii. Large signal tuned amplifiers.

21. Define resonant frequency.

The frequency at which the inductive reactance is equal to the capacitance reactance is called resonance frequency.

22. What are the conditions of resonance?

i. Impedance is maximum

ii. Minimum current

23. Define bandwidth of a tuned circuit.

The bandwidth of a tuned circuit is defined as the band of frequencies between the points in the resonance curve when the impedance drops to 1/√2 its maximum value at resonance.

24. Define selectivity.

Selectivity is defined as the ratio of the bandwidth of the circuit to its resonant frequency.

Selectivity = Bandwidth/Resonant frequency

25. What is meant by double tuned amplifier?

If the amplifier has two inductively coupled tuned circuits which are tuned to same frequency, then the amplifier is called double tuned amplifier.

26. What is meant by Stagger tuning?

In this amplifier, number of single tuned amplifiers are connected in cascade and tuned to slightly different frequencies.

27. How single tuned amplifiers are classified?

i. Capacitance coupled amplifiers

ii. Inductance coupled amplifiers

28. What are the advantages of tuned amplifiers?

i. Good SNR

ii. Amplify desired frequencies

iii. Suitable for radio transmitter and receiver

29. What are the disadvantages of tuned amplifiers?

i. Can't amplify audio frequencies

ii. Complex design

iii. Circuit is bulky

iv. Expensive

30. Why do we need neutralization?

To prevent oscillations in tuned amplifiers, the neutralization technique is used.

31. How is neutralization achieved in amplifiers?

i. Reduce Q

ii. Stagger tuning

iii. Loose coupling between the stages

32. What are the types of neutralization.

i. Hazeltine neutralization

ii. Neutrodyne neutralization

iii. Rice neutralization

iv. Neutralization using coil

33. What do you mean by Hazeltine neutralization?

The variable capacitor is connected to the base of the transistor which cancels the internal capacitance.

34. What are the advantages of Neutrodyne neutralization?

i. Capacitor is insensitive to variations in VCC

ii. High stability

 

REVIEW QUESTIONS

1. What do you mean by multistage amplifiers? Explain briefly.

2. Why a power amplifier is called large signal amplifier? Explain.

3. What is the difference between voltage and power amplifier?

4. What is a tuned voltage amplifier? Explain.

5. Discuss the frequency response of single tuned amplifier.

6. Draw the circuit diagram of a double tuned amplifier and explain its frequency response.

7. Compare the frequency response of double tuned amplifier with that of single tuned amplifier.

8. What is stagger-tuning? How it is employed in the tuned voltage amplifier?

9. What do you mean by BIMOS amplifier? Explain?

10. Explain the FET cascade amplifier in detail.

11. What is differential amplifier? Explain.

12. Discuss briefly about common mode gain and differential gain.

13. Explain the construction and operation of basic differential amplifier.

14. What are the types of differential amplifier? Explain.

15. What is CMRR? How can it be improved?

16. Explain the operation of differential amplifier using FET.

17. Discuss the concept of MOSFET differential amplifier.

18. What do you mean by Q-factor? Explain in detail.

19. Compare single tuned, double tuned and stagger tuned amplifier.

20. What do you mean by neutralization? Explain.

21. What are the methods of neutralizing tuned amplifiers?

22. Compare the efficiencies of various types of power amplifiers.

23. Explain the techniques used for neutralization with neat diagram.