# Digital Electronics Viva Questions (Part-1)

## Digital Electronics Viva Questions

Digital Electronics Viva Questions, Digital Circuit Systems Viva Questions, Analog Circuits Viva Questions, Digital Circuits Viva Questions, Engineering Viva Questions, Digital Electronics Viva Questions

Q.1. What is an analog signal? Give two examples of analog signals.

Ans. A signal which can assume any value in a given range is known as an analog signal. A sinusoidal signal and amplitude modulated signal are analog signals.

Q.2. What is a digital signal? Give two examples of digital signals.

Ans. A signal which can assume only two possible values is known as a digital signal. Voltage levels 0 V and 5 V, and the presence or absence of pulse are digital signals.

Q.3. Differentiate between analog and digital signals.

Ans. An analog signal is continuous and can assume any value in a given range, whereas a digital signal can have only two discrete values.

Q.4. What are the two kinds of electronic circuits?

Ans. The two kinds of electronic circuits and systems are- analog and digital.

Q.5. What are analog circuits? Give a few examples.

Ans. Analog circuits, are those electronic circuits in which voltages and currents vary continuously through the given range They can take infinite values within the specified range. Signal generators, radio frequency transmitters and receivers, power supplies, electric motors, and speed controllers are some examples of analog devices, or we can say analog circuits are electronic circuits meant to process analog signals.

Q.6. What are digital circuits?

Ans. Digital circuits are those electronic circuits in which the voltage levels can assume only a finite number of distinct values.

Q.7. Why digital circuits are called switching circuits?

Ans. Digital circuits are often called switching circuits because the voltage levels in a digital circuit are assumed to be switched from one level to another instantaneously, that is, the transition time is assumed to be zero.

Q.8. How are switching circuits classified?

Ans. Switching circuits are classified as (a) combinational switching circuits and (b) Sequential switching circuits.

Q.9. What are sequential circuits?

Ans. The switching circuits whose output depends not only on the present inputs but also on the present state (past history, i.e., on past inputs also) are called sequential circuits.

Q.10. What are synchronous sequential circuits?

Ans. Synchronous sequential circuits are those sequential circuits in which the state transitions take place only if the inputs are applied along with a clock pulse.

Q.11. How are sequential switching circuits classified?

Ans. Sequential switching circuits are classified as (a) synchronous sequential switching circuits and (b) asynchronous sequential switching circuits.

Q.12. What are asynchronous sequential switching circuits?

Ans. Asynchronous sequential circuits are those sequential circuits in which the state transitions can take place any time the inputs are applied.

Q.13. Why are digital circuits called logic circuits?

Ans. Digital circuits are also called logic circuits because each type of digital circuit obeys a certain set of logic rules.

Q.14. What do you mean by circuit logic?

Ans. The manner in which a logic circuit responds to input is referred to as the circuit’s logic.

Q.15. What are the advantages of digital systems over analog systems? What is the chief limitation to the use of digital techniques?

Ans. Digital systems have a number of advantages over analog systems. Digital systems are more versatile, easier to store daft, easier to design, less affected by noise, more accurate and precise than analog systems. The only major drawback of digital techniques is that “the real world is not digital, it is analog”.

Q.16. What is a hybrid system?

Ans. Systems in which both analog and digital techniques are applied in the same system are called hybrid systems.

Q.17. Name the three stages of digital system design?

Ans. The three stages of digital system design are system design, logic design, and circuit design.

Q.18. What do you mean by system design? Give an example.

Ans. System design involves breaking the overall system into subsystems and specifying the characteristics of each such system. For example, the system design of a digital computer involves specifying the number and type of memory units, arithmetic units, and input-output devices, as well as specifying the interconnection and control of those subsystems.

Q.19. What do you mean by logic design? Give an example.

Ans. logic design involves determining how to interconnect basic logic building blocks to perform a specific function. An example of logic design is determining the interconnection of logic gates and flip-flops required to perform binary addition.

Q.20. What is circuit design?

Ans. Circuit design involves specifying the interconnection of specific Components such as resistors, transistors, and diodes to form a gate, flip-flop, or any other logic building block.

Q.21. What is a positive logic system?

Ans. A positive logic system is one in which the higher of the two voltage levels represents logic 1, and the lower of the two voltage levels represents logic 0.

Q.22. What is a negative logic system?

Ans. A negative logic system is one in which the higher of the two voltage levels represents logic 0 and the lower of the two voltage levels represents logic 1.

Q.23. What do you mean by the amplitude of a pulse?

Ans. The amplitude of a pulse is the height of the pulse, usually expressed in volts.

Q.24. Define the rise time and fall time of a pulse.

Ans. The time taken by the pulse to rise from LOW to HIGH is called the rise time and the time taken by the pulse to fall from HIGH to LOW is called the fall time, but because of the nonlinearities that commonly occur at the bottom and top of the pulse, the rise time is defined as the time taken by the pulse to rise from 10% to 90% of the pulse amplitude, and the fall time is defined as the time taken by the pulse to fall from 90% to 10% of the pulse amplitude.

Q.25. Define pulse width.

Ans. The pulse width is defined as the time between 50% points on the rising and falling edges.

Digital Electronics Viva Question (Part-2)