(SEM III) THEORY EXAMINATION 2022-23 DIGITAL ELECTRONICS

This question paper is designed to assess a student’s understanding of Digital Electronics, covering number systems, logic gates, combinational and sequential circuits, logic families, and memory systems. The paper is divided into three sections—A, B, and C—each evaluating different levels of conceptual, analytical, and design-based skills.

SECTION A — Short Answer Questions (10 × 2 = 20 Marks)

Section A contains ten compulsory questions, each requiring brief but conceptually correct responses. The questions test:

Fundamental digital concepts like signed binary numbers, universal gates, and combinational circuits.

Understanding of codes (BCD), storage elements, sequential logic, and clock usage.

Basics of synchronous circuits, logic families, and fan-in parameters.

This section evaluates a student’s theoretical knowledge and ability to define and explain digital electronic terms concisely.

SECTION B — Descriptive / Analytical Questions (Any 3 × 10 = 30 Marks)

Section B contains five descriptive questions, out of which any three must be attempted.

These questions require:

Conversion between number systems (binary, octal, decimal, hexadecimal).

Designing digital circuits like 4:1 multiplexers using logic gates.

Understanding and explaining characteristic equations of SR and JK flip-flops.

Applying state reduction techniques used in sequential circuits.

Studying logic families, especially TTL, along with their characteristics and applications.

The section focuses on the application, derivation, and deeper conceptual understanding of digital logic design.

SECTION C — Long / Design-Based Questions (Any 1 from each unit × 10 = 30 Marks)

Section C has five units, each offering one of two options. Students must attempt one question from each unit.

The questions test:

Unit 1

Design of XOR gate using only NAND gates (gate-level implementation)
OR

De-Morgan’s theorem for simplifying SOP and POS expressions.

Unit 2

Design of a 4-bit binary adder using logic gates
OR

Design of a 3:8 decoder circuit.

Unit 3

Working of Serial-in Serial-out (SISO) shift register
OR

Design and explanation of a Modulo-5 counter.

Unit 4

Concept and applications of Asynchronous sequential circuits
OR

Types of hazards, their detection, and reduction.

Unit 5

Design and working of an SRAM cell
OR

Working and applications of Programmable Logic Array (PLA).

This section assesses the student’s ability to design, derive, and explain complete circuits with diagrams and correct logic.

Overall Purpose of the Question Paper

This examination tests a student’s ability to:

Understand and apply fundamental concepts of digital systems.

Perform number system conversions, logic minimization, and circuit design.

Analyze and design both combinational and sequential digital circuits.

Demonstrate knowledge of logic families, memory elements, and programmable logic devices.

Derive equations, draw timing diagrams, and logically explain digital operations.

The paper ensures that students possess both theoretical clarity and practical circuit design skills, essential for higher-level digital electronics and computer engineering courses.