Coventor Blog

MEMS+ 4.0: Removing the Barrier between MEMS and ASIC designers

By Steve Breit, V.P. Engineering
MEMS sensors never stand on their own – there’s always an accompanying ASIC that conditions the MEMS output or controls the MEMS. We’ve written frequently in past blogs and white papers about the barrier between MEMS and ASIC design teams. For purposes of functional verification, the ASIC designers need a MEMS block on their schematics, with an underlying model that captures the behavior of the MEMS. The problem arises because the MEMS and ASIC design teams use fundamentally different approaches to simulate the functioning of their respective designs. The MEMS designers use finite element analysis tools while the ASIC designers use analog/mixed-signal circuit simulators such as Cadence Spectre. There’s simply no way to include a conventional finite element model in a circuit simulator, and even if there was the simulations would run so slowly that it would have no practical use. To overcome this incompatibility, all MEMS companies that we’ve engaged with rely on handcrafting models of their MEMS devices in a hardware description language like Verilog-A that is compatible with the ASIC team’s circuit simulator. It takes lots of time, specialized knowledge, and skills to handcraft and verify a MEMS device model in Verilog-A. Because of the technical difficulty, handcrafted models are typically overly simplified, omitting important aspects of the MEMS behavior such as cross coupling between mechanical modes and non-linear effects. Moreover, an ongoing effort is needed to keep the handcrafted models in sync with the actual MEMS design, leaving plenty of opportunities for version skew and human error. The end result, undoubtedly, is extra design spins that are costly not only in engineering time, but in longer time to market. The graphic below illustrates this barrier.
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MEMS Executive Congress: Focus on Mobile

The MEMS Executive Congress (November 7-8 in Napa, Calif.) is a great annual event that brings together important stakeholders from throughout the MEMS ecosystem – MEMS developers, foundries, developers of MEMS-enabled products and design tool companies such as Coventor. We look forward every year to hear about important trends, technology developments and new applications areas – and, of course, meet up with long-time friends within the industry.

It’s no surprise that this year’s event is focused on mobile as mobile devices are driving growth and opportunity in the MEMS industry. Smart phones, tablets, games, and cameras are all increasing their MEMS content with a broad array of new capabilities that enable users to interact with their environment. Add in the growing trend for wearable computing – for health, sports, education and entertainment applications – and mobile products are clearly the key focal point for MEMS. As one observer pointed out, “mobile devices are quickly becoming the planet’s foremost wireless sensor network.” read more…

Virtual Fabrication: Not just for ICs. Better insight into manufacturing helps MEMS designers, too.

With the current focus on IC processing challenges at sub-20nm device length scales, interest in micron-scale wafer processing seems to be out of the limelight. However, in the world of MEMS, micron-scale processing is dominant for high-volume components such as gyroscopes and accelerometers. In a typical MEMS process flow, tens of microns of silicon are etched to release structural features that are a few microns wide. And while those in IC process integration may think that MEMS processing should be simpler than for leading-edge ICs, the increasing complexity and customization in MEMS designs raise a different set of processing issues, which demand further understanding for successful device manufacturing. read more…

Predicting the Future of MEMS

Technology market analysts have a long and storied history of making bold predictions and eye-opening forecasts for growth in the industries they follow. Many, if not most, of these tend to quietly get swept under the rug when unforeseen macro-economic events or truly disruptive technology innovations interrupt the smooth ‘up-and-to-the-right’ growth lines that analyst like to paint. This is especially true in long-range forecasts, where blue-sky predictions of double, even triple, digit growth can be made for several years hence, with little chance that there will be any long-term accountability held against the forecaster if and when the numbers fall short. read more…

Our persistent quest for more accuracy, speed and capacity

By Steve Breit, V.P. Engineering

During a visit to a prospective customer a few months ago, a MEMS design manager told me that her philosophy is that a simulation is not worth doing if it takes more than two hours. I don’t want to focus on whether two minutes, two hours or two days is the right threshold, the point is that all engineers have a time limit on how long they’re willing to wait for simulations to complete. That said, two to four hours sounds about right to me as an upper limit. The question is: what should engineers do when they can’t achieve acceptable accuracy within their self-imposed time limit?
Sometimes the right answer is to buy a faster, bigger computer. Thanks to Moore’s law, computers are continually getting faster and cheaper. It’s amazing how much computing power can be purchased for $5,000 these days. That may be a very smart investment compared to the cost of engineering time, not to mention lost time-to-market opportunity, squandered by using inadequate computers. If only it was this simple. Engineers have this pesky habit of wanting to simulate ever more complex designs with more complex physics, and do it accurately. Thus the expectations for simulation tools continue to outpace the increases in computing power.
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A Trillion Sensors? Not so unbelievable

There is no doubt that MEMS is an interesting market to watch within the semiconductor sector. Various market researchers forecast it to continue to outpace the growth of the overall semiconductor industry, expanding from its base of around $11 billion in sales to $22.5 billion within the next five years (source: Yole Development).

And there’s one school of thought that believes the opportunity for MEMS may be even greater than we might imagine. The Trillion Sensor Roadmap is a group of sensor industry visionaries and experts who predict that by 2023, the cumulative shipment volume of sensors will have reached one trillion. Some think the milestone will be reached even sooner. The group will explore this idea at its annual Sensor Summit event, held this year October 23-25 at Stanford University.
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