Quite Universal Circuit Simulator

Quite Universal Circuit Simulator (Qucs) is an open-source electronics circuit simulator software released under GPL. It gives you the ability to set up a circuit with a graphical user interface and simulate the large-signal, small-signal and noise behaviour of the circuit. Pure digital simulations are also supported using VHDL and/or Verilog.

Qucs supports a growing list of analog and digital components as well as SPICE sub-circuits. It is intended to be much simpler to use and handle than other circuit simulators like gEDA or PSPICE.

Analysis types

Analysis types include S-parameter (including noise), AC (including noise), DC, Transient Analysis, Harmonic Balance (not yet finished), Digital simulation (VHDL and Verilog-HDL) and Parameter sweeps.

Features at a glance

QUCS has a graphical interface for schematic capture. Simulation data can be represented in various types of diagrams, including Smith-Chart, Cartesian, Tabular, Polar, Smith-Polar combination, 3D-Cartesian, Locus Curve, Timing Diagram and Truth Table.

The documentation offers many useful tutorials (WorkBook), reports (ReportBook) and a technical description of the simulator.

Other features include the transmission line calculator, Filter synthesis, Smith-Chart tool for power and noise matching, Attenuator design synthesis, Device model and subcircuit library manager, Optimizer for analog designs, the Verilog-A interface, Support for multiple languages (GUI and internal help system), Subcircuit (including parameters) hierarchy, Powerful data post-processing possible using equations and symbolically defined nonlinear and linear devices.

Tool suite

Qucs consists of several standalone programs interacting with each other through the GUI.

The GUI is used to create schematics, setup simulations, display simulation results, writing VHDL code, etc.

The analog simulator is a command line program which is run by the GUI in order to simulate the schematic which you previously setup. It takes a netlist, checks it for errors, performs the required simulation actions, and finally produces a dataset.

The text editor is used to display netlists and simulation logging information, and to edit files included by certain components (e.g. SPICE netlists, or Touchstone files).

The filter synthesis application can be used to design various types of filters.

The transmission line calculator can be used to design and analyze different types of transmission lines (e.g. microstrips, coaxial cables).

The component library manager holds models for real life devices (e.g. transistors, diodes, bridges, opamps). It can be extended by the user.

The attenuator synthesis application can be used to design various types of passive attenuators.

The command line conversion program tool is used by the GUI to import and export datasets, netlists and schematics from and to other CAD/EDA software. The supported file formats as well as usage information can be found on the manpage of qucsconv.

Additionally, the GUI steers other EDA tools. For digital simulations (via VHDL) the program FreeHDL ^[1] is used. For circuit optimization (minimization of a cost function), ASCO ^[2] is configured and run.

Components

The following categories of components are provided:

• Lumped components (R, L, C, amplifier, phase shifter, etc.)
• Sources
• Probes
• Transmission lines
• Nonlinear components (diodes, transistors, etc.)
• Digital components
• File containers (S-parameter datasets, SPICE netlists)
• Paintings

There is also a Component library that includes various standard components available in the market (bridges, diodes, varistors, LEDs, JFETs, MOSFETS, and so on).

Transistor models

QUCS provides many transistor models. These include:

• FBH-HBT
• HICUM L0 v1.12
• HICUM L0 v1.2
• HICUM L2 v2.1
• HICUM L2 v2.22
• HICUM L2 v2.23
• MESFET (Curtice, Statz, TOM-1 and TOM-2)
• SGP (SPICE Gummel-Poon)
• MOSFET
• JFET
• EPFL-EKV MOSFET v2.6.

See also

• Comparison of EDA Software
• List of free electronics circuit simulators

References

External links

• Official website
• FreeHDL home page
• Icarus Verilog home page
• Win32 Binaries for Qucs and freehdl