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System Modeling Blog

6 May, 2013

EDA vs. Windows 8

Posted by Mike Jensen

Mike Jensen I have read a lot in recent months about Windows 8, Microsoft’s latest incarnation of its flagship Windows operating system. While there are many new features over and above its Windows 7 predecessor, one thing that makes me quite curious about Windows 8 is its optimization for touchscreen technology. Note that I have yet to use Windows 8, but I have used several other touchscreen devices on the market … Read More

25 Mar, 2013

VHDL-AMS Stress Modeling – Part 3

Posted by Mike Jensen

Mike Jensen I’ve been away from my blog for a couple of months helping the SystemVision Engineering team with a few details related to our upcoming release: SystemVision 5.10. We’re excited about this new release. It introduces, among other things, a new way to create simulation models from a variety of data sources. We think this new capability will make it much easier to create SystemVision simulation models. … Read More


28 Jan, 2013

VHDL-AMS Stress Modeling - Part 2

Posted by Mike Jensen

Mike Jensen


Part 1

of this series I started work on a simple resistor model as a way to illustrate some of the flexibility the VHDL-AMS language offers when creating simulation models. Recall that one of the advantages of VHDL-AMS is adding detail to models – a benefit not available with all modeling languages or methods. With VHDL-AMS, it’s possible to get your model and simulator to report performance details not available with other tools. To illustrate this flexibility, my resistor model will include a power dissipation calculation, and a comparison of the result with a user defined power limit to determine stress conditions.

Before jumping into the next model piece, however, I’ll tie up a loose end I left dangling in my earlier post. I mentioned the use of “==” when formulating device equations in a VHDL-AMS model. And at that time I said to simply interpret the syntax as “equal to”. But that definition doesn’t quite cover what’s going on inside the simulator. The “==” is more accurately interpreted as “balance both sides of the equation”. Once the simulator generates a matrix of equations that represent the system, the unknowns are adjusted during simulation, through a series of iterations, until all equations are solved within a user defined accuracy.

Now back to my resistor model. I’m going to jump right into the next architecture, so if you need a review (or a preview) of the model so far, take a quick look at Part 1. Up to this point it’s a basic Ohm’s Law-based resistor: voltage across the resistor is directly proportional to the product of the current and resistance. Now it’s time to add commands to calculate the power.

Recall once again from your first physics or electric circuits class that the power dissipated in a resistor is dependent on any two of its three operating parameters: voltage, current, resistance. There are a few different combinations of these parameters that calculate power, but I’ll use the following:

power = voltage x current

Based on this equation, here is the next section in my model:

1: architecture power1 of resistor is

2: quantity vres across ires through p1 to p2;

3: quantity pwr : power;

4: begin

5: vres == ires*res;

6: pwr == v*i;

7: end architecture power1;

Here I’ve created a new architecture named “power1” for the resistor model. This architecture is the same as the “basic” architecture in my earlier post, except that its name is changed and Lines 3 and 6 are added to setup the power calculation. Line 3 defines a new quantity named “pwr” (remember that a quantity is an analog element in a model) with an assigned VHDL-AMS type of “power”. Note that pwr is not directly associated with the p1 and p2 ports of the model. Therefore the type assignment simply determines what units will be used (in this case “watts”) to plot the pwr quantity. Line 6 calculates pwr as the product of the voltage across the resistor and the current through it, as define in the standard power equation above. This architecture can be added to the model in Part 1 to create a resistor model with one entity and two architectures (recall that a VHDL-AMS model can only have one entity, but multiple architectures). When I use the resistor model in a SystemVision schematic, I can select which architecture to use for that resistor instance. If I choose the power1 architecture, the resistor’s power is calculated at each time or frequency step during the simulation, and becomes a waveform I can plot when the simulation is finished.

Now that my basic resistor is complete, I can add details that will determine if the power exceeds a user defined power rating. In Part 3 of this series I’ll create another new architecture that detects when the resistor’s power exceeds a user defined limit, and notifies me when there is a problem.

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7 Jan, 2013

VHDL-AMS Stress Modeling - Part 1

Posted by Mike Jensen

Mike Jensen One of the great values of modeling with a hardware description language is simply this: you can tell a model to calculate and report all sorts of information about what’s happening inside it. Consider a generic electrical model, for example. Simulators will report voltages across and currents through the device. But what if you want to know how much power is dissipated in the device? Or if the power … Read More

10 Dec, 2012

Practice! Practice!

Posted by Mike Jensen

Mike Jensen I recently attended a piano recital for a young man in my neighborhood who studies  music at a local university. He has natural musical aptitude and is an awesome piano talent. During his recital he played compositions from popular yet long since deceased composers: Beethoven, Liszt, Debussy, Prokofiev. If you’re not familiar with any of these names, not to worry. I only know them because my wife’s … Read More

Engineering Design

9 Nov, 2012

Sharing Tool Expertise

Posted by Mike Jensen

Mike Jensen In my last post I talked about using modeling and simulation to preserve design and technical expertise within a company. This seems a valuable methodology for preventing technical ‘brain drain’ within a corporation. Recently, however, I ran into another simulation dilemma related to sharing simulation knowledge: how to share simulation expertise between companies. Often when I talk with … Read More


29 Oct, 2012

Preserving Expertise

Posted by Mike Jensen

Mike Jensen Like many youth since time began and there were pianos to play, my daughter takes piano lessons. In musical ways, she is much like her mom. Both play piano and sing beautifully. And like her mom, my daughter’s talent is several notches above average, at the level that leaves you wanting to hear more when each piece is over. I recently attended a recital to listen to my daughter and her fellow … Read More


11 Oct, 2012

Virtual Prototyping -- Really?

Posted by Mike Jensen

Mike Jensen I like books – lots of ‘em. I rarely turn down a chance to visit a bookstore or search Amazon’s gazillion pages for a book or two on whatever topic I’m interested in at the moment. Most of my personal library contains non-fiction books that explain how to do things. Over the years I’ve found that my book collection trends toward a few categories, the largest of which are Writing, Engineering, Programming, … Read More

SystemVision conneXion, Mechatronic, LabVIEW, Simulink

4 Oct, 2012

Innovations in Motion Control Design

Posted by Mike Jensen

Mike Jensen It certainly isn’t news that I think Mechatronics is a pretty cool field of study. Whether you design and build mechatronic systems for your profession or your hobby (or maybe both), you have to admit it’s a fascinating subject. As I write this, I’m waiting anxiously for FedEx (or perhaps UPS) to deliver my latest toy – a 2006 Mini Cooper S remote control (RC) car kit. I’ve owned several RC cars over … Read More

motion control, Mechatronics

28 Sep, 2012

Game Changers

Posted by Mike Jensen

Mike Jensen I’ll start this post, as I sometimes do, with a disclaimer: I am not a rabid football fan. I enjoy watching an occasional game, and my wife is an enthusiastic supporter of her college alma mater’s football team (think blue turf in Idaho), but I don’t live for the game. My wife does not become a football widow, nor my children football orphans, on weekends. Football is a pleasant pastime for me, … Read More


17 Sep, 2012

Do We Overdesign?

Posted by Mike Jensen

Mike Jensen

My daily driver (at least until my daughter gets her driver’s license in a few months) is a 1982 Honda Civic 1500 DX. It’s not much to look at – paint is faded and the upholstery needs extensive repair – but the body is pretty straight and it runs quite well for being 30 years old. Could I afford to drive something else? Yes. In fact, my family’s transportation fleet includes 4 other vehicles of 1998

Read More

7 Aug, 2012

Tsunami Remnants

Posted by Mike Jensen

Mike Jensen I’m back at my keyboard after a brief, but enjoyable, vacation. Like last year, I trekked with my family to the Oregon Coast. Yes, we enjoy time at the beach, though this time we travelled with extended family so we spent a bit more time driving around site seeing than playing in the tide. In seven days I personally logged some 1200 miles in the driver’s seat. Luckily I don’t mind … Read More


24 Jul, 2012

A New Look at Device Modeling

Posted by Mike Jensen

Mike Jensen 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 … Read More

Mixed-Signal, analog modeling

12 Jul, 2012

SystemVision 5.9

Posted by Mike Jensen

Mike Jensen It’s software release time in the SystemVision® offices, and I’m happy to announce that SystemVision 5.9 is ready for immediate download. Here are some of the release highlights: Design entry: User interface (UI) updates including more flexible user customization; Support for multi-sheet schematics and multi-view symbols; Improved schematic symbol generation; Easier mapping between simulation … Read More

6 Jun, 2012

Veyron Physics

Posted by Mike Jensen

Mike Jensen The Bugatti Veyron occupies a unique spot among dealer showroom trophy cars: the fastest production automobile in the world. With a top speed of 254 miles per hour (406 kilometers per hour), the Veyron sits atop the supercar heap, chewing up asphalt at a brisk pace just under 4.3 miles per minute (over 6.7 kilometers per minute). If a Veyron graced my humble two-car garage, I could theoretically travel … Read More

IEEE 1076.1, physics


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