Frequently Asked Questions¶

General¶

What is GeckoCIRCUITS?¶

GeckoCIRCUITS is an open-source power electronics circuit simulator written in Java. It supports multi-domain simulation including electrical, thermal, and EMI analysis. Originally developed at ETH Zurich, it's used in education and research.

What Java version do I need?¶

Java 21 or later. We recommend Eclipse Temurin.

Which operating systems are supported?¶

GeckoCIRCUITS runs on Windows, Linux, macOS, and WSL (Windows Subsystem for Linux). Platform-specific launcher scripts are provided in scripts/.

Is it really free?¶

Yes. GeckoCIRCUITS is dual-licensed under GPL v3 (free for open-source/academic use) and a commercial license for proprietary applications.

Simulation¶

What solver does GeckoCIRCUITS use?¶

GeckoCIRCUITS uses Modified Nodal Analysis (MNA) with fixed time-step solvers:

Backward Euler (BE) - Default, most stable
Trapezoidal (TRZ) - Better accuracy, can oscillate
Gear-Shichman (GS) - Multi-step method

How do I choose the right time step?¶

Rule of thumb: the time step should be at least 100x smaller than the switching period.

Switching Frequency	Recommended Time Step
10 kHz	< 1 us
100 kHz	< 100 ns
1 MHz	< 10 ns

Why is my simulation unstable?¶

Common causes:

Time step too large - Reduce it (see table above)
Algebraic loops - Add a small series resistance or inductance
Ideal switches - Add snubber circuits or use realistic switch models
Stiff system - Try the Backward Euler solver instead of Trapezoidal

Can I simulate thermal effects?¶

Yes. GeckoCIRCUITS supports coupled electro-thermal simulation:

Enable thermal nodes on semiconductor components
Define thermal resistance networks (Rth, Cth)
The simulator solves electrical and thermal equations simultaneously

See Thermal Simulation Tutorials.

What's the maximum circuit size?¶

There's no hard limit, but practical limits depend on your system RAM:

1000+ components - Typical desktop (8GB RAM)
Complex thermal networks - May need -Xmx3G or more
Very fast switching (>1MHz) - Long simulations will be slow with small time steps

Integration¶

Can I use GeckoCIRCUITS with MATLAB?¶

Yes, via the RMI (Remote Method Invocation) interface:

gecko = GeckoRemoteInterface('localhost', 1099);
gecko.setParameter('PWM.1', 'dutyCycle', 0.5);
gecko.runSimulation();

See MATLAB Integration Tutorial.

Can I use it with Python?¶

Yes, through:

File-based - Run simulations via subprocess, parse output files
REST API - The gecko-rest-api module provides HTTP endpoints
GeckoSCRIPT - Built-in scripting (JavaScript-like syntax)

See Python Integration Tutorial.

Can I use it with Simulink?¶

Yes. GeckoCIRCUITS provides an S-function for Simulink co-simulation. See the tutorial in resources/tutorials/7xx_scripting_automation/703_simulink_cosimulation/.

File Formats¶

What is an .ipes file?¶

The native GeckoCIRCUITS circuit file format. It's gzip-compressed text containing component data, connections, and simulation parameters.

Can I import SPICE netlists?¶

Not directly. GeckoCIRCUITS uses its own circuit format. You'll need to rebuild the circuit in the GeckoCIRCUITS editor.

Can I export simulation data?¶

Yes. Use the SCOPE component's export function to save waveform data as CSV files for analysis in MATLAB, Python, or Excel.