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A New Look at Device Modeling

Mike Jensen

Mike Jensen

Posted Jul 24, 2012

Lately I’ve been working with customers interested in using SystemVision to simulate either a real production design, or some sort of evaluation test circuit. To a customer, however, each ran into the “don’t have a simulation model” challenge for one or more devices in their system. Despite SystemVision’s large VHDL-AMS and SPICE model libraries, we didn’t have a suitable model match. And Internet searches didn’t turn up anything useful. So what is an engineer to do? The answer might be easier than you think.

SystemVision is a powerful and flexible modeling and simulation platform. Part of this power and flexibility is centered in the IEEE standard VHDL-AMS modeling language. Using VHDL-AMS, engineers can create device models of almost any type and complexity. A pretty good deal if you already know VHDL-AMS, but a pretty tough row to hoe if you first need to learn the language before creating any models. Fortunately, there is an easier way — Graphical Component Modeling.

Graphical Component Modeling (GCM) is a technique for building device models from simple, low-level building blocks. It’s kind of like having a modeling Erector Set: you have a box full of modeling pieces from which you can build an almost limitless variety of useful simulation models. With a little creative imagination and a bit of engineering inspiration, you can use GCM techniques to develop some pretty amazing models without writing a single line of VHDL-AMS code. In a way, GCM is like creating SPICE macromodels or Simulink control algorithm models, but with a couple of key differences.

First, GCM isn’t stuck modeling in a single discipline (think about the electrical-only limitations of SPICE). With SystemVision’s building-block library, it’s easy to create models in a variety of technologies, including models where the input technology is different from the output technology. Consider a pressure sensor, for example, where the input is a pressure, and the output might be a voltage or current. GCM simplifies device modeling, giving engineers a simulation toolbox full of building blocks for single and mixed-technology device modeling. Pretty cool stuff.

Second, GCM simplifies conserved system modeling using simple real number processing based on a library of math function building blocks. This is similar to control system-level signal-flow modeling for which Simulink is famous, but GCM also accounts for energy conservation in the device – not a common feature in signal-flow type models. How does this work? The answer is in SystemVision’s ability to efficiently and effectively model both conserved and signal-flow systems, which GCM uses to model physical behavior. The technique is simple: use signal-flow building blocks to model device functions, then wrap the signal-flow model in conserved building blocks to ensure energy conservation and accurate modeling of physical behavior.

Graphical Component Modeling truly is a powerful technique for developing sophisticated device models without the overhead of knowing (or learning) a new modeling language. In future posts I’ll introduce a few GCM-based model examples to illustrate GCM’s power and flexibility. Stay tuned…

In the mean time, post a comment and let me know what analog/mixed-signal/mixed-technology modeling challenges you see in your design work. GCM just might be a viable solution.

Mixed-Signal, analog modeling

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About Mike Jensen

Mike JensenMost career paths rooted in high technology take many interesting (and often rewarding) twists and turns. Mine has certainly done just that. After graduating in electrical engineering from the University of Utah (go Utes!), I set off to explore the exciting, multi-faceted high tech industry. My career path since has wound its way from aircraft systems engineering for the United States Air Force, to over two decades in applications engineering and technical marketing for leading design automation software companies, working exclusively with mechatronic system modeling and analysis tools. Along the way, I’ve worked with customers in a broad range of industries and technologies including transportation, communications, automotive, aerospace, semiconductor, computers, and consumer electronics; all-in-all a very interesting, rewarding, and challenging ride. In my current gig, I work on technical marketing projects for Mentor Graphics' SystemVision product line. And in my spare time I dream up gadgets and gizmos, some even big enough to qualify as systems, that I hope someday to build -- providing I can find yet a little more of that increasingly elusive spare time. Visit Mike Jensen's Blog

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Comments 2

Post a Comment
Does system have build blocks like Agilent's systemvue? yanfeng

Yanfeng yu
4:21 AM Jul 25, 2012

The building block modeling concepts between SystemVision and SystemVue are similar, though the model libraries and analysis options supported in each tool are different. SystemVision is tuned for mechatronic system design and analysis, while SystemVue is focused more on communications systems. You should be able to use VHDL-AMS to model communication system behavior, but SystemVision may not have all of the RF-focused analysis options you might expect from a communication systems-focused tool.

Mike Jensen
11:17 PM Jul 25, 2012

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