(SEM V) THEORY EXAMINATION 2022-23 ADVANCE DIGITAL DESIGN USING VERILOG

Course: B.Tech (Electronics / Electrical / Computer Engineering)

Semester: V                                                                     Subject Code: KEC-054

Title: Advance Digital Design Using Verilog                    Time: 3 Hours

Maximum Marks: 100

Exam Type: Theory Paper

Sections:

Section A: Conceptual / Short Answers – 20 marks

Section B: Descriptive / Design Questions – 30 marks

Section C: Analytical / Application-based Questions – 50 marks

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

All ten questions are compulsory and test basic understanding of digital and Verilog concepts.

Mixed Logic:

Mixed logic combines positive and negative logic conventions in digital systems for more efficient circuit design.

Don’t Care (X) Condition:

Represents unused input combinations in truth tables; used to simplify Boolean expressions during minimization.

Comparator:

A combinational circuit that compares two binary numbers and determines whether one is greater, equal, or smaller.

Boolean Function:

An algebraic expression consisting of binary variables and logic operations (AND, OR, NOT) representing a circuit’s behavior.

Optimization in Digital Design:

The process of reducing hardware (gates, transistors) while maintaining or improving performance.

Algorithm:

A finite set of well-defined steps to solve a logical or mathematical problem.

Fault:

A defect or malfunction in a digital circuit that causes incorrect output (e.g., stuck-at-0 or stuck-at-1 fault).

Factoring:

Rewriting Boolean expressions into simpler, equivalent forms to reduce gate count and delay.

Sequential Circuit:

A circuit whose output depends on both current input and previous state (e.g., flip-flops, counters).

Programmable Logic Family:

A group of integrated circuits like PLA, PAL, GAL, and FPGA that can be programmed for specific logic functions.

SECTION B – Descriptive Questions (3 × 10 = 30 Marks)

Attempt any three of the following:

Multiple Output Minimization Techniques:

Methods like K-map grouping for multiple outputs, Quine-McCluskey, and Espresso algorithm are used to minimize shared logic across outputs.

Design a 4:1 Multiplexer using Minimum Gates:

4:1 MUX can be designed using AND, OR, and NOT gates or two 2:1 MUX.

Logic:

• Y=S1′S0′I0+S1′S0I1+S1S0′I2+S1S0I3Y = S_1'S_0'I_0 + S_1'S_0I_1 + S_1S_0'I_2 + S_1S_0I_3Y=S1′​S0′​I0​+S1′​S0​I1​+S1​S0′​I2​+S1​S0​I3​

Mapping Algorithm:

A process to implement logic networks on FPGAs by assigning gates and functions to available resources efficiently.

Path Sensitization Methods:

Used in test vector generation to detect circuit faults; identifies input combinations that activate a specific fault path.

FPGA Architecture:

Consists of Configurable Logic Blocks (CLBs), Interconnects, and I/O blocks; used for custom hardware implementations.

 SECTION C – Analytical / Application-Based Questions (5 × 10 = 50 Marks)

Attempt one part from each question (Q3–Q7).

Q3

(a) XOR Pattern Handling:

XOR gates are crucial for parity generation, comparators, and error detection.

Efficient XOR pattern handling in synthesis improves area and timing.

(b) Logic Representation in Mixed Logic Design:

Involves representing both positive and negative logic symbols.

Used in mixed voltage or logic-level systems.

Q4

(a) Structural Specifications in Verilog:

Describes hardware interconnections at the gate or module level using assign and module statements.

Example: Building circuits by instantiating sub-modules.

(b) Design of 3:8 Decoder:

Uses three inputs (A, B, C) and eight outputs (Y₀–Y₇).      Each output represents a unique input combination.

Q5

(a) ASM (Algorithmic State Machine) Charts:

Graphical representation of sequential operations combining flowcharts and state diagrams.

Used in designing finite state machines.

(b) Multi-Level Minimization and Optimization:

Reduces logic across multiple hierarchical levels using factoring, decomposition, and common sub-expression elimination.

Q6

(a) BDD (Binary Decision Diagram):

Represents Boolean functions in graph form.

Used for circuit simplification, equivalence checking, and synthesis.

(b) Fault Detection Techniques:

Methods include path sensitization, fault simulation, parity checkers, and built-in self-test (BIST).

Q7

(a) ASIC (Application-Specific Integrated Circuit) Architecture:

Custom-designed IC optimized for a particular application.

Contains logic cells, memory, and routing resources.

(b) PLD (Programmable Logic Device) Architecture:

Comprises AND-OR arrays and programmable interconnects.

Common types: PLA, PAL, CPLD — used for configurable digital systems.

 Key Topics Covered

Boolean algebra and logic minimization                     Sequential and combinational circuit design

Verilog HDL design principles                                      FPGA / ASIC / PLD architectures

ASM charts and finite state machine design                Fault modeling and testability

Binary Decision Diagrams and optimization