Qucs-S: Qucs with SPICE

Download links

The latest stable release is Qucs-0.0.19S. It is based on stable Qucs-0.0.19: (Installation instructions...)

Contibuition guide

Qucs-S is open for everyone's contribution. See here for contribution guide.


Simulation example with Qucs-S and Ngspice

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What is Qucs-S?

Qucs-S is a spin-off of the Qucs cross-platform circuit simulator. "S" letter indicates SPICE. The purpose of the Qucs-S subproject is to use free SPICE circuit simulation kernels with the Qucs GUI. It merges the power of SPICE and the simplicity of the Qucs GUI. Qucs intentionally uses its own SPICE incompatible simulation kernel Qucsator. It has advanced RF and AC domain simulation features, but the most of existing industrial SPICE models are incompatible with it. Qucs-S is not a simulator by itself, but it requires to use a simulation backend with it. The schematic document format of Qucs and Qucs-S are fully compatible. Qucs-S allows to use the following simulation kernels with it:


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Main features



Debian repository

Debian repository ("Jessy" and "Wheezy") is available for Qucs-S. Packages are built with automatic Open Build Service (OBS) tool from OpenSUSE team. Go to download repository You need to perform the following steps to add this repository in system (for Debian 9). For othe distributions simple replace the URLs. If you have problems with adding repository in your system you can download and install the *.deb package manually with dpkg:

dpkg -i qucs-s-0.0.19S_amd64.deb
You may need to install the following dependencies: lib4qt4-qt3support, ibqt4-svg, ngspice

Building from source

If your Linux distribution is not Debian-based, then you will need to build Qucs-S from source: The complete command sequence to build Qucs-S is following:

tar xvfz qucs-0.0.19S.tar.gz
cd qucs-0.0.19S
mkdir builddir
cd builddir
cmake ..
make install

The last command make install should be executed from root user. It will install Qucs-S into default prefix /usr/local/. No additional configure options are needed now.

Slackware SlackBuild

Slack Build script is available for Slackware distribution. It will download and compile Qucs-S automatically. You will obtain the binary Qucs-S package. Perform the following steps to install Qucs-S:
  1. Clone this repository:
    git clone https://github.com/ra3xdh/QucsS.SlackBuild
  2. Run SlackBuild as root:
    cd QucsS.S.SlackBuild
  3. Install txz package with installpkg command


You need to use binary installer for Windows. You need to download and install Ngspice and/or XYCE manually from official websites: http://ngspice.org/ https://xyce.sandia.gov respectively. It's recommended special build of Ngspice-26 for Windows Ngspice26_QucsS.zip . Default Ngspice package also will work but it may have some limitation. Custom Ngspice build solves the following issues:



Run qucs-s from the the command line or launch Qucs-S icon in your desktop environment menu after the installation. You will need to select default simulation backend at the first run. You can change it later in the application settings.


Launch Qucs-S in the system Start menu. You will also need to select default simulator on the first application start. You will need to set default simulator at the first run. Correct simulator paths setting is necessary for Windows.

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Contribution guide

Steps to contribute

Use qucs-s-stable branch fore quick pre-release fixes, and spice4qucs_current for new features. Don't use Perform the following commands to contribute into spice4qucs_current:

git clone -b git clone -b spice4qucs_current https://github.com/ra3xdh/qucs
cd qucs/qucs
git checkout -b your_feature
You can find more detailed information about branching model and

Branching model

Currently there are three main branches in my home Qucs repository:

Release tarball is obtained from qucs-s-stable with some Bash script. This script removes Qucsator and microwave utilities from Qucs-S codebase. I distribute only Qucs-GUI and some utilities with Qucs-S package.

My changes only concentrated on GUI side, and you need to rebuild GUI only to test Qucs-S. You may take Qucsator from usual Qucs installation.

Build instruction (development branches)

For qucs-s-stable you need to set WITH_SPICE cmake key. Autotools will not work. Perform the following commnads to build all:

git clone https://github.com/ra3xdh/qucs/ -b qucs-s-stable
cd qucs/qucs
mkdir build
cd build

Then install and launch qucs-s executable.

For spice4qucs_current you may use traditional Qucs build instructions. You may need to rebuild only Qucs-GUI. Autotools also may not work here, and it's recommended to use CMake:

git clone https://github.com/ra3xdh/qucs/ -b spice4qucs_current
cd qucs/qucs
mkdir build
cd build
cmake .. -DCMAKE_INSTALL_PREFIX=/some_path

Then install and launch qucs binary. (to top...)


Qucs-S is not a simple circuit simulator, but also a research software. Please cite our articles, if you are using Qucs-S in your research.
  1. Brinson, M. E., and Kuznetsov, V. (2016) A new approach to compact semiconductor device modelling with Qucs Verilog-A analogue module synthesis. Int. J. Numer. Model., 29: 1070–1088. (BibTeX)
  2. D. Tomaszewski, G. Głuszko, M. Brinson, V. Kuznetsov and W. Grabinski, "FOSS as an efficient tool for extraction of MOSFET compact model parameters," 2016 MIXDES - 23rd International Conference Mixed Design of Integrated Circuits and Systems, Lodz, 2016, pp. 68-73. (BibTeX)
  3. M. Brinson and V. Kuznetsov, "Qucs-0.0.19S: A new open-source circuit simulator and its application for hardware design," 2016 International Siberian Conference on Control and Communications (SIBCON), Moscow, 2016, pp. 1-5. (BibTeX)