January 09, 2012
Blurring the line between EDA & Test
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Charles continued, "Additional evidence supporting the trend that linking EDA and measurement is a growing field is that others are taking interest in this space. For example, in recent months National Instruments decided to acquire Applied Wave Research. At NI Week in Austin, NI started to share its future vision for linking EDA software to its instrumentation. Also Synopsys announced that it would collaborate with the Rhode & Schwarz hardware company on a software validation library for the emerging LTE (Long-term Evolution) phone standard. So there is plenty of evidence to support the existence of a new market
dynamic here," said Charles.
So in this EDA WEEKLY article, in collaboration with Agilent and others, the writer explores several specific areas and examples where EDA and Measurement have become more intertwined. As you will see, this is not necessarily a new trend, but it is an increasing trend one and it’s getting more attention given the companies involved, their growing investments and their declared strategies.
Device Modeling – One of the First Areas where EDA meets Measurement
Every EDA circuit simulator requires some level of transistor model. It turns out that most of these models originate in a blended world of EDA and Measurement. In some cases, the actual measured data
is the model (more on this later). Given that the transistor model is at the heart of most designs, its accuracy is of critical importance. A further proof point is that EDA companies, foundries, and the top-tier companies designing communication products all have investments in what is called “Device Modeling.” It is arguably the first place where the world of EDA and the world of Measurement cross paths.
The writer was fortunate to have the opportunity to speak with one of Agilent’s modeling software experts, who enthusiastically shared some insights about Measurements and EDA and its importance to Agilent. “Having a credible modeling solution is a fundamental requirement for EDA suppliers – in other words, simulation alone is a partial solution – you have to have a core expertise in modeling,” said
Dr. Roberto Tinti, of Agilent’s device modeling software team.
“Agilent sees ‘modeling’ as a strategic investment on both the software and measurement/hardware side, knowing that this is one of the top issues of designers in many segments of the industry. It is important for us to continue demonstrating both innovation and technical leadership in this area,” Dr. Tinti continued. “I learned that it really comes down to this: device models are only as good as the measured data that is used to extract them, so measurement expertise is critical to be able to gather accurate and meaningful device data for modeling. Today there is an entire EDA segment where
dedicated software is used not only to control the measurements, but also to optimize the extraction of compact model device parameters based on a series of specific measurements.”
“Today we offer products like IC-CAP and WaferPro, not only to control the instruments (and even the probe station), but also to help collect, interpolate, and refine the measurements so they can be used in EDA design tools and circuit simulators downstream,” said Dr. Tinti. “This not only saves our customers time, but also helps provide them with the most accurate models for their simulations.”
That there are other companies participating in this space ratifies its advantages.
Accelicon, an EDA supplier based in Cupertino CA and China, and specializing in device characterization, has found an important niche offering software focused on helping companies validate the accuracy of their models against the myriad of measurements that get made.
So once again, EDA and Test are not so independent.
As briefly mentioned above, there are some interesting technical advancements where the actual measurement itself is used as the device model. Dr. Tinti explains, “Device modeling for compound semiconductors has always been challenging. There are many effects like carrier trapping, thermal and non-quasi-static, that strongly influence the device behavior and are very difficult to model using traditional compact models (equation-based). In addition, new materials like GaN (gallium nitride) are now being used for high voltage, high power devices and no accurate compact device models are available. To fill these gaps companies like ours are
exploring artificial neural network technology to extract models that are entirely based on measurements.”
So here’s another case where the concept of separate EDA and Measurement worlds is no longer valid at all – the measurement itself is embedded in EDA.
X-parameters Advance Active Component Simulation and Measurement
Many of the same observations in the last section can be extended to modeling in general (not just at the transistor level). In high-frequency design, modeling linear networks has been dominated by a technology known as "S-parameters." Like voltages and currents, S-parameters have been the long-standing figure of merit for anyone doing high-frequency communications design. Entire categories of EDA simulators (linear simulators, electro-magnetic simulators, filter synthesis tools, etc.) have been built for producing S-parameters. In the measurement world, there exists a several hundred million dollar industry supplying network analyzers for this
More recently, there has been a technical breakthrough called
"X-parameters" that this writer first mentioned in the EDA WEEKLY article of March 29, 2010:
Like S-parameters, X-parameters™ is a category of network parameters that allow engineers to completely characterize nonlinear circuits or systems with a measurement. So, again, as in the device modeling case, the measurement itself is used within the EDA simulation.
“X-parameters are one of the more interesting technical innovations that have hit the RF and Microwave market in recent years,” said
Dr. Larry Dunleavy, President of Modelithics, Tampa, FL. “Nonlinear modeling and measurement has always been a challenge and we have seen some encouraging results as we work with customers providing modeling and measurement services.”
Other industry players on the measurement side see the trend as well. “We’ve been working with Agilent since 2008 on the proof-of-concept and integration of Load Pull with X-parameters and have seen a growing interest from our customers,” said
Greg Maury, President and Chief Executive Officer of Maury Microwave, Ontario, CA. “As a device characterization measurement and modeling solutions provider, X-parameters allow our 'load pull' customers to create nonlinear models of their non-50ohm active devices and use them directly with EDA tools, something that has been requested for years.”
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-- Russ Henke, EDACafe.com Contributing Editor.
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