Basic Electronics Important questions units 4 (FAQ)

Unit-4:  Operational Amplifiers – Introduction to OP Amp, characteristics and applications – Inverting and Non-inverting Amplifiers, Summer, Integrator, Differentiator, Instrumentation Amplifier.

Digital System: Basic Logic Gates, Half, Full Adder and Subtractors.


  1. What are the four basic building blocks of Op-Amp explain each block in detail. 10M.
  2. Write in detail about Instrumentation amplifier.
  3. Design and realize Full Subtractor (Give the necessary expression and Truth table and Circuit diagram)

Short Answer questions:     

  1. What are the ideal characteristics of OP-AMP?
  2. What is an operational amplifier? Mention some of its applications.
  3. A 5mV, 1 kHz sinusoidal signal is applied to the input of an OP-amp integrator for which R=100KΩ and C=1µF.Find the output voltage.
  4. What are the different parameters of an OP-amp? Sketch the circuit of a summer using OP-amp 741to get Vo= -(-V1+2V2-3V3).
  5. Write a note on basic logic gates.
  6. Draw the truth table of an EX-OR gate.
  7. State and prove De-Morgan’s theorems. Discuss the working of half adder and full adder and give their truth tables.
  8. Write a note on universal gates.
  9. Realize OR gate using NAND gates.
  10. What is half Subtractor? Realize full Subtractor using using NAND gate only.
  11. What is an op-amp? List the four building blocks of an op-amp.
  12. Draw the schematic symbol of an op-amp in detail. Write the expression for output voltage of an op-amp?
  13. What are the applications of op-amp?
  14. What are the advantages of op-amp?
  15. Why op-amp is named as op-amp?
  16. What are universal gates and why those are called as universal gates?
  17. Draw EX-OR and EX-NOR gates and give the truth tables of each gate.
  18. Name some basic logic gates draw their symbols and give the corresponding truth tables.
  19. Draw half adder and half Subtractor.

Long Answer questions:

  1. Draw and explain block diagram of op-amp in detail. Or what are the basic building blocks of an op-amp explain in detail.
  2. Write in detail about
  3. Half adder/ Full adder.
  4. Full Subtractor/ Half Subtractor.
  5. Explain the operation of inverting and non-inverting amplifier circuits using op-amp and calculate gain of each circuit in closed loop configuration.
  6. Define common mode rejection ratio (CMRR).a differential amplifier has a differential mode gain of 100 and common mode gain of 0.01 then find CMRR in dB?
  7. Write in detail about instrumentation amplifier.
  8. Explain the operation of the following circuits of op-amp in open loop configuration.    a. Non –inverting amplifier.        b.   Inverting amplifier  c.  Differential amplifier.
  9. What are the characteristics of practical op-amp?
  10. Define slew rate of op amp? Problem on calculation of Slew rate.
  11. Explain how op-amp is used as  Summer and difference amplifier or Subtractor.


Prepared by                                                                                       P.Lakshmi Prasanna


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Author: Lakshmi Prasanna

Completed M.Tech in Digital Electronics and Communication Systems and currently working as a faculty.