Free / Open-Source EDA Tools for VLSI Learning
Commercial EDA tools are expensive, but you can still learn a lot using free & open-source tools. Below is your original blog content, plus additional practical info on purpose + where/how to download.
✅ What each tool is used for (Quick Overview)
If you are a fresher: start with RTL simulation → learn synthesis → explore OpenLANE to understand the complete flow.
Many of VLSI engineer searching for VLSI CAD tools where they can enhanced their skill-sets , but all of VLSI tools comes with a great cost , but you can still download some of the free tools. Below is the Info.
So, What are EDA tools in VLSI ?
Electronic design automation (EDA), also referred to as electronic computer-aided design (ECAD), is a category of software tools for designing electronic systems such as integrated circuits and printed circuit boards.
Here is some of EDA tools used in semiconductor Industry.
1. RTL simulations free tools
There is modelsim student version available on official Mentor Graphics website, one can download and use it for educational projects , it ha some limitations.
https://modelsim.informer.com/6.5/
🔍 Extra details: ModelSim Student Version (How to get + use)
How to use: Create project → add RTL + testbench → compile → simulate → view waves.
Alternative (fully free): Use Icarus Verilog (iverilog + vvp) or Verilator for fast simulation on Linux.
2. DFT simulation free tools
Tessent/ synthesis tool can be used for DFT insertion , but they are not available free. Synthesis tools comes with a huge cost to company , one can try on Xilinx website
🧪 Extra details: How to learn DFT without Tessent
Commercial DFT tools (Tessent/DFT Compiler) are not free, but you can still learn the concepts: scan chains, stuck-at faults, ATPG basics, MBIST, boundary scan.
3. Physical Design free Tools
Innovus from Cadence used for place and route and CTS building , this is also not available free of cost.
🏗 Extra details: Free Physical Design learning tools
Innovus is commercial. For learning PD (floorplan, placement, CTS, routing), the most practical free approach is using OpenLANE/OpenROAD with Sky130.
4. Spice simulation free tools
LTSpice tool is available for download and one can use it for educational purpose.
https://www.analog.com/en/design-center/design-tools-and-calculators/ltspice-simulator.html
⚡ Extra details: LTspice (what to simulate + where to get)
5. Timing analysis free tools
Tempus from Cadence or PrimeTime from Synopsys used in Timing analysis and final sign-off the design, unfortunately , they are not available free of cost.
⏱ Extra details: Timing analysis (free learning path)
PrimeTime/Tempus are commercial. For learning STA basics (setup/hold, slack, constraints), explore OpenTimer and OpenROAD/OpenLANE reports.
6. Design-architecture/diagram free tools.
Many tools are available to build diagram/micro-architecture blocks, Visio was there but it is not free , however some evaluation version can be found online.
Some more open source CAD tools available.
This is a general-purpose drawing program and also a specific-purpose CAD program for circuit schematic drawing and schematic capture.MyHDL
It is a Python package for using Python as a hardware description language
FreePCB
This tool is to generate metal layers and vias to physically connect together a netlist in a VLSI fabrication technology. It is a maze router, otherwise known as an "over-the-cell" router or "sea-of-gates" router.
NetGen
Netgen is a tool for comparing netlists, a process known as LVS, which stands for "Layout vs. Schematic". This is an important step in the integrated circuit design flow, ensuring that the geometry that has been laid out matches the expected circuit. Very small circuits can bypass this step by confirming circuit operation through extraction and simulation. Very large digital circuits are usually generated by tools from high-level descriptions, using compilers that ensure the correct layout geometry. The greatest need for LVS is in large analog or mixed-signal circuits that cannot be simulated in reasonable time. Even for small circuits, LVS can be done much faster than simulation, and provides feedback that makes it easier to find an error than does a simulation.
Netgen version 1.5 is considered complete and competitive with commercial-grade tools. Code was added to handle device properties and to resolve parallel combinations of devices whether individually instantiated or implied through the use of the "M" property. Serial and parallel networks of passive devices are analyzed and compared between networks.
Netgen version 1.4 is an attempt to bring netgen up to par with the industry-standard Calibre tool from Mentor Graphics. Since (as far as I know) all LVS tools are based on the same class partitioning algorithm, this effort is not as difficult as it may seem. Mostly, netgen must be made to properly understand hierarchy, device properties, and generate a more readable output. All these changes are now completed (as of November 2007, when the development version 1.4 branch was created). The hierarchical LVS was partially completed in 2010, and in version 1.4.35 (October 2012) it is considered done (apart from necessary bug fixes). Version 1.4.35 also includes a full side-by-side comparison for the output format.
Netgen was written by Massimo Sivilotti, and eventually incorporated into the beginnings of the Tanner L-Edit suite of tools. However, the original code was left open source, and so I have incorporated it into the Tcl-based suite of tools including magic, IRSIM, and xcircuit.
MAGIC
Magic is a venerable VLSI layout tool, written in the 1980's at Berkeley by John Ousterhout, now famous primarily for writing the scripting interpreter language Tcl. Due largely in part to its liberal Berkeley open-source license, magic has remained popular with universities and small companies. The open-source license has allowed VLSI engineers with a bent toward programming to implement clever ideas and help magic stay abreast of fabrication technology. However, it is the well thought-out core algorithms which lend to magic the greatest part of its popularity. Magic is widely cited as being the easiest tool to use for circuit layout, even for people who ultimately rely on commercial tools for their product design flow.
Alliance
complete set of free CAD tools and portable libraries for VLSI design. It includes a VHDL compiler and simulator, logic synthesis tools, and automatic place and route tools. A complete set of portable CMOS libraries is provided, including a RAM generator, a ROM generator and a data-path compiler.
That's right, Electric is free software, an official GNU package. You can download the full version of Electric right now.
There is no better way to get to know a CAD system than to use it for a while. Now you can use it at no charge! If you like it, keep it! If you don't, you've lost nothing.
Verilator
Verilator is the fastest free Verilog HDL simulator. It compiles synthesizable Verilog, plus some PSL, SystemVerilog and Synthesis assertions into C++ or SystemC code. It is designed for large projects where fast simulation performance is of primary concern, and is especially well suited to create executable models of CPUs for embedded software design teams.
DipsLab
2. Synopsys
3. Mentor Graphics
4. Xilinx
5. Tanner
6. Electric
7. Silvaco
8. Glade
9. Alliance
some more added here.
Yosys for synthesis
Covered : Can be used to find code Coverage
Open Timer : Is a static timing analysis engine
Synthesis to GDSII Flow:
🚀 ASIC Design Job Openings (Freshers)
If you're a fresher looking for ASIC Design / Verification openings, check this updated page:
📖 Digital Design Interview Questions (Must Read)
If you are preparing for interviews, read this: https://rtldigitaldesign.blogspot.com/2021/05/digital-design-interview-question-on_1.html
Digital Design Interview Questions & Answers
Quick access to frequently asked digital design questions (freshers friendly).
- FSM, counters, mux/encoder basics
- Setup/Hold and timing concepts
- Combinational vs sequential logic
