Engineers Garage

  • Electronic Projects & Tutorials
    • Electronic Projects
      • Arduino Projects
      • AVR
      • Raspberry pi
      • ESP8266
      • BeagleBone
      • 8051 Microcontroller
      • ARM
      • PIC Microcontroller
      • STM32
    • Tutorials
      • Audio Electronics
      • Battery Management
      • Brainwave
      • Electric Vehicles
      • EMI/EMC/RFI
      • Hardware Filters
      • IoT tutorials
      • Power Tutorials
      • Python
      • Sensors
      • USB
      • VHDL
    • Circuit Design
    • Project Videos
    • Components
  • Articles
    • Tech Articles
    • Insight
    • Invention Stories
    • How to
    • What Is
  • News
    • Electronic Product News
    • Business News
    • Company/Start-up News
    • DIY Reviews
    • Guest Post
  • Forums
    • EDABoard.com
    • Electro-Tech-Online
    • EG Forum Archive
  • DigiKey Store
    • Cables, Wires
    • Connectors, Interconnect
    • Discrete
    • Electromechanical
    • Embedded Computers
    • Enclosures, Hardware, Office
    • Integrated Circuits (ICs)
    • Isolators
    • LED/Optoelectronics
    • Passive
    • Power, Circuit Protection
    • Programmers
    • RF, Wireless
    • Semiconductors
    • Sensors, Transducers
    • Test Products
    • Tools
  • Learn
    • eBooks/Tech Tips
    • Design Guides
    • Learning Center
    • Tech Toolboxes
    • Webinars & Digital Events
  • Resources
    • Digital Issues
    • EE Training Days
    • LEAP Awards
    • Podcasts
    • Webinars / Digital Events
    • White Papers
    • Engineering Diversity & Inclusion
    • DesignFast
  • Guest Post Guidelines
  • Advertise
  • Subscribe

Introduction to VHDL & Verilog – DE Part 9

By Hai Prasaath K October 23, 2018

In the previous tutorials, boolean functions, boolean expressions, minimization of boolean expressions and implementation of a boolean function into logic gate diagram was discussed. It is possible to minimize a boolean function with less number of boolean variables and implement a logic gate diagram for it manually. But as the number of variables in a boolean function increases, not only its minimization becomes complex, designing a logic gate implementation for it also becomes cumbersome. In such case, computer based design tools are the ultimate resort.

These digital circuit design tools use hardware description language to describe, prototype and test a digital circuit. A Hardware Description Language is a programming language that describes the hardware architecture and functioning of a digital circuit in the form of text. A hardware description language basically describes the relationship between the input signals to a digital circuit and the output signals from it. In this way, it can textually represent any truth table, boolean function or boolean expression. The HDL generally have a syntax that is both readable by humans as well as software tools (design applications).

Fig. 1: Representational Image for Hardware Description Languages

The design process of a digital integrated circuit using HDL involves the following steps –

1) Design Entry: This is the first step in the designing of a digital integrated circuit. In this step, HDL is used to describe the functionality of the digital circuit. The description can be in the form of truth table, boolean equation, netlist of interconnected logic gates or behavioural models. A large and complex digital circuit may be divided into small functional units or models that are then interconnected with each unit having its own functionality and behaviour.

2) Logic Simulation: In this step, the digital circuit based on the HDL statements is simulated either as time ordered sequence of input and output signals or in the waveform of the input and output signals. The simulation of the digital circuit is useful in detecting any error in the logical design of the circuit even before its fabrication on a chip. The logic values of the input signals that are used to simulate the digital circuit are called test bench. The test bench is also written in HDL. By simulating the digital design, the errors in the logic of the circuit are detected and the respective HDL statements are then corrected to derive the desired output signals.

3) Design Synthesis: In this step, the digital circuit is programmatically synthesized as a database of physical components required and their interconnections. The interconnection of physical components of the digital circuit is called netlist. This database can be used to fabricate the circuit either on a silicon chip or as layout on a printed circuit board. The digital database generated by synthesis tools is useful in automating the fabrication of the digital integrated circuit as the actual procedures involved in the implementation of the digital circuit are incorporated within the database.

4) Timing Verification: The digital circuits must output signals within a desired time limit. There is some propagation delay in the signal when it transits from one logic gate to another. Practically, this propagation delay must be minimized (like by two-level implementation of the boolean functions in the circuit). By time verification, the speed of the digital circuit is confirmed. The process involves checking each signal path and confirm that it is not compromised by the propagation delays. This is the final step before the fabrication of the digital circuit.

5) Fault Simulation: Before the circuit is produced, it is compared with the ideal circuit as initially described in the HDL. The production circuit may not exhibit the same behaviour as the ideal circuit in case there may induce some fault in the circuit. The production circuit must be verified being fault free before shipping. The fault simulation is always done before production to test the internal logic of the integrated circuit.

6) Physical Design: In the process, the digital circuit is fabricated on a silicon chip or PCB inside a clean room. This is the production stage of the circuit. The circuit must be fabricated in a dust free environment. Even a single dust particle can cause fault in the functioning of the circuit.

There are two standard Hardware Description Languages – VHDL and Verilog. VHDL is an abbreviation of VHSIC Hardware Description Language where VHSIC stands for Very High Scale Integrated Circuit. VHDL is a IEEE standard HDL language mandated by Department of Defence. The Verilog is a proprietary HDL language from Cadence Design Systems. The Cadence has transferred the control of Verilog to a consortium of companies and universities known by name – Open Verilog International. The OVI Verilog is developed as an adoption for IEEE standard. The Verilog is simple to use and learn compared to VHDL.

In the next tutorial, learn about arithmetic circuits. The arithmetic circuits are the basic digital circuits that are the part of an arithmetic Logic Unit (ALU) in any Central Processing Unit (CPU).


Filed Under: Digital Electronics, Tutorials

 

Next Article

← Previous Article
Next Article →

Questions related to this article?
👉Ask and discuss on EDAboard.com and Electro-Tech-Online.com forums.



Tell Us What You Think!! Cancel reply

You must be logged in to post a comment.

EE TECH TOOLBOX

“ee
Tech Toolbox: 5G Technology
This Tech Toolbox covers the basics of 5G technology plus a story about how engineers designed and built a prototype DSL router mostly from old cellphone parts. Download this first 5G/wired/wireless communications Tech Toolbox to learn more!

EE Learning Center

EE Learning Center
“engineers
EXPAND YOUR KNOWLEDGE AND STAY CONNECTED
Get the latest info on technologies, tools and strategies for EE professionals.

HAVE A QUESTION?

Have a technical question about an article or other engineering questions? Check out our engineering forums EDABoard.com and Electro-Tech-Online.com where you can get those questions asked and answered by your peers!


RSS EDABOARD.com Discussions

  • Identification of a 6 pin smd chip (sto-23-6) marked E2
  • Dynacord enter protect
  • IGBTs without negative gate drive
  • Need suggestions in task NI6363 retrigger (analog trigger)
  • Monte-Carlo simulation error on ADE-XL

RSS Electro-Tech-Online.com Discussions

  • Faulty heat air gun (dc motor) - problem to locate fault due to Intermittent fault
  • Does US electric code allow branching ?
  • Fun with AI and swordfish basic
  • Sump pit water alarm - Kicad 9
  • turbo jet fan - feedback appreciated.

Featured – LoRa/LoRaWan Series

  • What is the LoRaWAN network and how does it work?
  • Understanding LoRa architecture: nodes, gateways, and servers
  • Revolutionizing RF: LoRa applications and advantages
  • How to build a LoRa gateway using Raspberry Pi
  • How LoRa enables long-range communication
  • How communication works between two LoRa end-node devices

Recent Articles

  • How IoT network topologies work
  • The top five AI startups to watch in 2025
  • STMicroelectronics unveils SoC based on secure MCU
  • Nexperia’s 48 V ESD diodes support higher data rates with ultra-low capacitance design
  • Taoglas releases Patriot antenna with 18 integrated elements covering 600 to 6000 MHz

EE ENGINEERING TRAINING DAYS

engineering

Submit a Guest Post

submit a guest post
Engineers Garage
  • Analog IC TIps
  • Connector Tips
  • Battery Power Tips
  • DesignFast
  • EDABoard Forums
  • EE World Online
  • Electro-Tech-Online Forums
  • EV Engineering
  • Microcontroller Tips
  • Power Electronic Tips
  • Sensor Tips
  • Test and Measurement Tips
  • 5G Technology World
  • Subscribe to our newsletter
  • About Us
  • Contact Us
  • Advertise

Copyright © 2025 WTWH Media LLC. All Rights Reserved. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media
Privacy Policy

Search Engineers Garage

  • Electronic Projects & Tutorials
    • Electronic Projects
      • Arduino Projects
      • AVR
      • Raspberry pi
      • ESP8266
      • BeagleBone
      • 8051 Microcontroller
      • ARM
      • PIC Microcontroller
      • STM32
    • Tutorials
      • Audio Electronics
      • Battery Management
      • Brainwave
      • Electric Vehicles
      • EMI/EMC/RFI
      • Hardware Filters
      • IoT tutorials
      • Power Tutorials
      • Python
      • Sensors
      • USB
      • VHDL
    • Circuit Design
    • Project Videos
    • Components
  • Articles
    • Tech Articles
    • Insight
    • Invention Stories
    • How to
    • What Is
  • News
    • Electronic Product News
    • Business News
    • Company/Start-up News
    • DIY Reviews
    • Guest Post
  • Forums
    • EDABoard.com
    • Electro-Tech-Online
    • EG Forum Archive
  • DigiKey Store
    • Cables, Wires
    • Connectors, Interconnect
    • Discrete
    • Electromechanical
    • Embedded Computers
    • Enclosures, Hardware, Office
    • Integrated Circuits (ICs)
    • Isolators
    • LED/Optoelectronics
    • Passive
    • Power, Circuit Protection
    • Programmers
    • RF, Wireless
    • Semiconductors
    • Sensors, Transducers
    • Test Products
    • Tools
  • Learn
    • eBooks/Tech Tips
    • Design Guides
    • Learning Center
    • Tech Toolboxes
    • Webinars & Digital Events
  • Resources
    • Digital Issues
    • EE Training Days
    • LEAP Awards
    • Podcasts
    • Webinars / Digital Events
    • White Papers
    • Engineering Diversity & Inclusion
    • DesignFast
  • Guest Post Guidelines
  • Advertise
  • Subscribe