LibrePDK: Difference between revisions
| Line 93: | Line 93: | ||
There's two types of resistor structures available: Meander and strip resistors | There's two types of resistor structures available: Meander and strip resistors | ||
LibrePDK automatically adds a guard ring around any resistor which should be on a well | |||
=== The meander here is 200 Ohms for GF180A@3.3V === | |||
[[File:LibrePDK Meander Example.png|none|thumb|300x300px]] | [[File:LibrePDK Meander Example.png|none|thumb|300x300px]] | ||
=== The meander here is 500 Ohms for GF180A@3.3V === | |||
[[File:Strip Resistor Example.png|none|thumb|300x300px]] | |||
== Transistors == | == Transistors == | ||
For now there's only single gate transistors (fingered transistors are still WIP) | For now there's only single gate transistors (fingered transistors are still WIP) | ||
Revision as of 00:36, 26 May 2026
The LibrePDK is the library driving Danube River and the Pad Cell Generator
It is responsible for generating discrete parts with specific parameters for a specific process.
The properties of the parts can be optimized by utilizing the calibration values extracted from the measurements of taped out Danube River test wafers.
Adding a new technology
Technologies currently supported can be found in the technologies subfolder.
New technologies can be added by modifying scripts/update_technologies.sh and adding a tech.python script to the technologies folder.
After that, LibrePDK should be capable of auto discovering the new process after running the update script.
Installation
First please clone the repo
pip install https+git://gitlab.libresilicon.com/generator-tools/librepdk.git
Don't forget to make sure that all the submodules and their submodules are cloned
git submodule update --init --recursive
For placement of discrete componentes used in more complex components like Driver Circuits, OpAmps, etc. IdeaPlaceExPy is being used.
IdeaPlaceExPy requires the Python system headers to be installed and the virtual env has to match the Python version with which it was compiled.
Using LibrePDK in a Virtual Environment
It is recommended to use LibrePDK in a Python virtual environment to avoid dependency conflicts with system-wide Python packages.
After you've installed all the below dependencies the recommended way of installing the remaining dependencies is to run
uv sync --no-cache
OpenVAF models
IHP's SG13G2 technology node uses OpenVAF models for the ngspice simulation tool.
The following script will make sure that rust and the OpenVAF tool are present and then compiles the models into the osdi format and places them into the technology directory ready to be used by LibrePDK.
Simply run the following script and confirm the installation by checking for the LibrePDK/technologies/spice/SG13G2/devices/*/*.osdi files.
./scripts/update_ngspice_extensions.sh
LP solver
Google now officially runs the project and you can get the most recent version from GitHub
Install is by cloning and building it
git clone https://github.com/lp-solve/lp_solve
pushd lp_solve/lpsolve55
rm -rf bin/ux64
sh ccc
popd
Then you can copy the shared object file in solve/lpsolve55/bin/ux64 into your /usr/lib64 and copy the headers with
mkdir /usr/include/lpsolve
cp lp_solve/*.h /usr/include/lpsolve/
OR, you can install the system package and devel package with your package manager
Lemon
That library has been developed by a Hungarian university which doesn't maintain their Mercurial setup. Best approach is to use the version you find in your distribution
Limbo
The official version of Limbo has been a total mess when it comes to building libs and linking them. I had to make some severe modifications which makes CMake properly build shared object files and detects the system wide installation of the dependencies using proper CMake detection functions
Just run
git clone https://gitlab.libresilicon.com/leviathan/limbo.git
mkdir Limbo/build
pushd Limbo/build
cmake ..
make
make install
popd
Components
LibrePDK provides generators for the basic components usually found within a VLSI/ULSI design, such as resistors, capacitors and transistors.
Capacitors
LibrePDK can calculate the specific geometry based on the device rules and available parameters for generating any desired target capacitance value. Below a 50pF capacitor can be seen. You will notice the enormous dimensions of the structure.
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Usually we deal with femto Farad in VLSI design so you should never be in a situation where you have large capacitors on your chip.
LibrePDK still can generate you a device, you just won't be happy about it.
Resistors
There's two types of resistor structures available: Meander and strip resistors
LibrePDK automatically adds a guard ring around any resistor which should be on a well
The meander here is 200 Ohms for GF180A@3.3V
The meander here is 500 Ohms for GF180A@3.3V
Transistors
For now there's only single gate transistors (fingered transistors are still WIP)