This document is a B.Tech (Semester IV) Theory Examination Question Paper for the subject BEE401 – Digital Electronics, conducted for the academic session 2023–2024.
It is a 3-hour, 70-mark examination designed to assess students’ understanding of number systems, logic gates, combinational and sequential circuits, logic families, flip-flops, multiplexers, ADC/DAC, and digital system design.
The paper is divided into three sections—A, B, and C—ranging from short conceptual questions to advanced circuit design questions.
SECTION A – Short Answer Questions (14 Marks)
Seven 2-mark questions on fundamental digital electronics topics:
Decimal-to-binary conversion (37₁₀ → binary)
Explanation of Universal Gates (NAND, NOR)
Meaning of Combinational Circuit
Definition of Half Adder
Advantages & disadvantages of ECL Logic Family
Meaning of Fan-in and Fan-out
Advantages of CMOS Logic Family
These questions evaluate basic definitions, functions, and digital logic fundamentals.
SECTION B – Intermediate-Level Circuit Design & Logic Problems (21 Marks)
Students must attempt any three of the following:
Simplification of Boolean expression:
F(A,B,C,D) = Σm(1,3,7,11,15) + d(0,2,5)
Design of 32:1 Multiplexer using 8:1 and 4:1 MUX
State table, state diagram, and state equation for Clocked JK Flip-Flop
Operation of TTL NAND gate in tri-state configuration
Implementation + operation of 3-input NOR Gate using CMOS and DTL logic families
These problems test circuit design ability, Boolean simplification, and understanding of digital logic families.
SECTION C – Advanced Digital Electronics Questions (28 Marks)
Each question contains two options; one must be attempted from each.
3. Boolean Expression Conversions & K-Map Minimization
Convert expressions to Standard POS Form:
(i) AB + AC + BC
(ii) A + BC + ABC
Minimize SOP expression using K-map:
Y = A̅B̅C̅ + A̅BC̅ + A̅BC + AB̅C
4. Algorithm & Multiplexer Logic
Flowchart showing subtraction algorithm using Adder
Implement F(A,B,C,D) = Σm(0,2,3,6,8,11,12,14) using Multiplexer
5. Sequential Logic – Flip-Flops & Shift Registers
Working of Master–Slave JK Flip-Flop with logic diagram
Modes of operation & applications of Shift Register
6. Logic Family Comparison & CMOS Gate Operation
Performance comparison of TTL, CMOS, ECL Logic Families
Operation of CMOS NAND and CMOS NOR with neat diagrams
7. Data Converters (ADC/DAC)
Meaning + working of R-2R Ladder DAC
Types of ADCs and operation of Dual Slope ADC
This section evaluates deep understanding of sequential circuits, ADC/DAC design, multiplexer-based implementation, and advanced logic family behavior.
Overall Purpose of the Document
This exam paper evaluates a student's complete understanding of:
Number systems and Boolean algebra
Logic gates (TTL, CMOS, ECL)
Combinational circuits (MUX, adder, NOR, POS/SOP forms)
Sequential circuits (JK flip-flop, shift registers)
K-map simplification
Algorithmic flowcharts
Data converters (ADC, DAC)
Circuit design using digital logic families
The paper includes numerical conversions, logic simplification, diagrams, state modeling, and implementation-based questions—ensuring a full assessment of digital electronics knowledge.
