Design Simulation Systems Ltd

The Legacy Simulation Stuff

In an era where an electronic circuit is a slab of silicon, designed by writing a language like VeriLog or VHDL, with virtually no need to understand the mathematics of circuit design, or the physics of semiconductor devices, we present a set of tools from a more gracious age. From an age when computers were still drawn by horses, and it took an engineer to design something. Not a software package.

I guess this is all precipitated by the fear that, one day, there will be nobody left who actually understands how or why stuff like VHDL works, and colleges will have stopped teaching mathematics, because it's all too hard, and too many people fail the courses - which isn't politically correct, because it damages their delicate egos....

So, what are these analog tools? I hear you ask...

At some point, you might like to see a complete electronic circuit design cycle, starting with schematic capture, proceeding to a time-domain simulation, and finishing with some DSP post-processing of the result, to produce a Fast Fourier Transform of the output waveform

These tools are all available for free download, compiled for either Linux or Sun SPARC and, if you have Cygwin, the stuff even runs on Windows. No special gizmos, like Motif or Java are needed, and they'll run quite happily on anything with a working X11 library.

If your boredom threshold is fairly high, there's an application note showing how to do Hierarchical Analog Design, using the example that comes with the SPICE manual.

Graphical Schematic Capture and Edit
Of course, circuit design is done with a graphical circuit editor, supported with libraries for everything. Behavioural level Laplace Transform primitives, high level logic functions, semiconductors, mechanical components, PCB track primitives and a heap of others.
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FFT, IFT And A Lot More
When the simulation is finished (or if you have your input data in a file), you can apply a whole heap of mathematical functions, including forward and inverse Fourier transforms, convolution, deconvolution, differentiation, integration functions and display results in the complex plane.
You can also download either the SPICE or Spice3 simulator (or both), each of which has functionality that the other doesn't have. Both simulators have been enhanced with LIMPTS increased to 65536, and memory to 800000. They both continuously dump node data to a binary file
Find out more Find out about DSP functions

High Level Digital Logic Simulator
Not content with offering the analog circuit creation and simulation anachronism, we compound the injury by also showing a digital circuit simulator, which simulates digital logic at the device level, not the gate level.
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Oscilloscope, Spectrum Analyser, Signal Generator
You can set up any waveform you can think of with the signal generator, drive your circuit over whatever time interval, and with whatever resolution you choose, and watch the outputs change. This goes for a time domain analysis, a frequency domain sweep and everything else that SPICE can do. All results are presented graphically.
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SPICE Models From Data Sheets

Since even the most comprehensive library may miss the very device which you need to use, we also supply a set of component modelling tools

Vmodel will make a computer model from the characteristics supplied on the data sheet, while Vmodel2 accepts X-Y characteristic curve data, and accurately extracts and optimizes the relevant SPICE parameters by curve-fitting techniques

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Free Downloads

All the analog tools mentioned above are available as Cygwin, Linux or SPARC executables. If you're planning on using GEX, you're going to need the analog lib file, which also contains SPICE models for a whole variety of stuff, and you'll probably need the netlist compiler, GSP. Of course, you can always make your netlists by hand...
There are also Unix man pages for most of the products, which you can install in any 'man' directory.
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Can't make it work on your version of Linux?

Need to model an obscure semiconductor device?

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