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′S0I1+S1S0′I2+S1S0I3
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
