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Timing the IoT

Editor’s note: We welcome a new guest blogger this week: Alan K. Mond, EVP Sales and Marketing, Sand 9 Inc.

Click on any tech article today and chances are the subject matter will be about the huge growth in IoT (Internet of Things). From smartphones to wearables, from smart thermostats to smart lighting, and from smart cars to smart industry, everybody is looking to capture a share of what is expected to be the largest growth market in the next three to five years, and MEMS is playing a key role in enabling differentiation across the value chain.

Fundamentally, IoT is an ecosystem where devices that either contain or have access to sensors are connected to the Internet via a broadband connection, either wired or wireless. Industry reports on market size vary. Last year Gartner published its forecast, “The Internet of Things, Worldwide 2013,” and suggests that the total number of connected devices will grow to 26 billion by 2020, which will provide $1.9 trillion in economic value-add, whereas Cisco Systems puts that number at 50 billion devices and the “value at stake” at $14.4 trillion. Regardless of the final market size, it is clear that the growth in IoT will be unprecedented with respect to anything seen since the industrial revolution.

One major area that has helped enable the growth in IoT has been the availability of components and semiconductors that support these new smart devices. These items include sensors, controllers, and most importantly communications chips that support not only broadband cellular transmissions (3G and LTE), but also GNSS/GPS and other short-range wireless connectivity chips (WiFi, Bluetooth, ZigBee, etc.). A summary table of protocols and applications is listed below.

As the number of ICs supporting the above protocols has increased, the number of semiconductor companies offering connectivity integrated circuits (ICs) to IoT OEMs has also grown. Heightened competition in a standards-dominated market is driving semiconductor companies to seek out opportunities to differentiate by offering lower cost and smaller size, while enabling new features. The drive to differentiate is creating new opportunities for MEMS.

Figure 1

IoT will drive a new generation of ICs with advanced circuit/system design, packaging, and even new technology, such as MEMS timing.

IoT will drive a new generation of ICs with advanced circuit/system design, packaging, and even new technology, such as MEMS timing.

One important trait all the ICs share is the need to be clocked by a reliable reference source. Today, quartz devices are ubiquitous components in all wireless communication devices. Despite their dominance, they are now under significant threat from silicon-based MEMS timing devices, which today offer a real alternative to quartz, with many advantages that are integral for success in IoT applications, for example:

Size/power. Quartz crystals are limited in size, due to the physics required to maintain a size-to-thickness ratio. This poses a significant dilemma for the semiconductor designer. Ideally, semiconductor designers like to use low-frequency clock references in the range of 12-26 MHz. The use of lower frequencies reduces power consumed within the clocking system, which improves battery life. Unfortunately, at low frequencies the physics of quartz means that it is typically housed in a large, 3.2×2.5 mm ceramic package, external to the IC in question.

Designers can opt to move to higher frequencies, resulting in smaller package sizes, but this ultimately leads to higher power consumption. MEMS resonators, in contrast, do not suffer from the same physical constraints as quartz. In fact, in the case of piezoelectric MEMS resonators, frequencies from 12 MHz to 150 MHz can be obtained without trading off size. Today, piezoelectric MEMS resonators are available in an ultra-small 0.72×0.80 mm CSP, a reduction of over 14X when compared to traditional quartz. This size advantage also allows semiconductor designers (for the first time) to integrate timing with their ICs to offer a true system-on-chip (SoC) or system-in-package (SiP) solution to their customers.

Resistance to shock and vibration. Quartz crystals are extremely fragile, and susceptible to failure when subjected to repeated shock and/or vibration. MEMS, on the other hand, because of its low resonator mass and monolithic structure, can withstand an order of magnitude greater level of both shock and vibration. This opens up new markets in industrial IoT applications where vibration can be a major cause of failure (e.g., wind turbines and engine management) as well as in consumer IoT applications that are subject to shock (Nike+ shoes, for example).

Cost. Unlike quartz crystals that are assembled individually, piezoelectric MEMS manufacturing is based on leveraging semiconductor manufacturing processes and wafer bonding techniques. Devices are built on 8-inch wafers at a density that allows for manufacturing costs lower than those of traditional quartz, enabling OEMs to reduce their overall BOM costs.

Today, the availability of piezoelectric MEMS timing devices provides a paradigm shift in the way the semiconductor industry considers timing for IoT applications. By integrating MEMS resonators, semiconductor companies can provide a differentiated SoC solution that offers new features, performance, and cost advantages to the evolving IoT market.

17 comments on “Timing the IoT

  1. geek
    November 25, 2014

    @Steve: Will piezoelectric MEMS timing devices prove to be the next breakthrough for IoT devices? Or will it have its restrictions and only cater to a selected set of IoT devices and not become an industry-wide norm?

  2. Steve Taranovich
    November 25, 2014

    @tzubair—Piexo MEMS will certainly replace the old quartz timing devices in the IoT. I see no reason why it would not become the heart of every IoT device going forward. (Until the next timing breakthrough, of course)

  3. samicksha
    November 26, 2014

    I havent seen integration of such MEMS but i think packaging piezoelectric can be little tough, considering their delicate nature and expense.

  4. Steve Taranovich
    November 26, 2014

    @samicksha—Please see my EDN article for details about Piezo MEMS packaging http://www.edn.com/electronics-products/electronic-product-reviews/other/4424798/Sand9–The-stealth-MEMS-timing-startup 

    You will see why it's far better than packaging quartz crystal solutions

  5. geek
    November 29, 2014

    “I see no reason why it would not become the heart of every IoT device going forward. (Until the next timing breakthrough, of course)”

    @steve: From a technical standpoint, MEMS do seem to be on the verge of breaking through into the IoT world. What would be interesting is how the cost factor comes into play and whether they are still able to make their way into IoT devices.

  6. Steve Taranovich
    November 29, 2014

    @tzubair—In the MEMS Journal, Dr. Hisham Haddara, founder of Si-Ware Systems (SWS) says:

    For the applications where MEMS based clocks compete, the cost will be generally lower than quartz by a significant percentage, provided that a good yield is achieved.  It is important to note that prices depend on the specifications and applications; also both quartz and MEMS based oscillator providers are continually pushing price down.  This is also an area where all silicon clocks (IC clocks) offer a clear advantage, since the resonating element is on the chip and does not add any extra cost.

  7. samicksha
    November 30, 2014

    Thank You Steve, this was really interesting and clear presentation with comparison and highlights, got little more understanding with this blog.

  8. geek
    November 30, 2014

    @Steve: Thank you for sharing the excerpt from the journal. So it does seem that MEMS based clocks are offering a better set of technical specifications and are also competing head-to-head in terms of the costs. This does make their future seem very bright as far as IoT is concerned.

  9. Sachin
    November 30, 2014

    Will piezoelectric MEMS timing devices prove to be the next breakthrough for IoT devices?

    @tzubair, looking at the advantages of MEMS timing device over quartz I am sure MEMS timing devices will definitely prove to be next breakthrough for IoT devices.

  10. Sachin
    November 30, 2014

    For the applications where MEMS based clocks compete, the cost will be generally lower than quartz by a significant percentage, provided that a good yield is achieved.

    @steve, what are the yield numbers for MEMS based clocks and how can we make sure that we achieve better yeild ?

  11. Sachin
    November 30, 2014

    Please see my EDN article for details about Piezo MEMS packaging

    @steve, thanks for sharing the link. Do you think quartz has better performance as we see in “Frequence error vs temperature” plot?

  12. Davidled
    December 1, 2014

    It is heard that GM releases the Wifi installed vehicle capable for internet access in coming year that I understand. Automaker also sell internet to buyers. It could be expected that internet could be free in the near future. This vehicle might have smart sensor related to IoT.

  13. amond
    December 1, 2014

    Sorry for the delay in responding to all the great questions, I was in northern Maine for thanksgiving with no internet or cell coverage, quite an experience.

     

    Regarding Piezoelectric MEMS in IoT applications, currently we are working with all the major Semiconductor players to integrate our MEMS with their IC's. The IC's that are using our technology cover the following protocols, Bluetooth 4.0, WiFi (including 802.11p), ZigBee, RF4CE, LTE, 2.4GHz and sub 1 GHz. Applications include wearables (including those that incorporate GPS), Smart Appliances, Smart Light Bulbs, Smart Thermostats, IoT toys, Remote controls, security system etc. We are also working with companies who's IoT products experience harsh environmental conditions. In these case our vibration immunity and high resistance to shock play a key role in our customers selection of our MEMS. Ultimately I see MEMS replace all quartz devices in IoT applications in the next 3-5 years.

  14. amond
    December 1, 2014

    Samicksha, there is no issue with over-molding our MEMS. The actual MEMS is protected with a silicon cap to provide hermeticity, but unlike Electro-static MEMS does not need to be sealed in a vacuum. There are no stress related issues with over-molding and our parts can be supplied with solder balls, copper pillars or just solder pads for wire-bonding. They can be placed in a System in Package (SiP) environment either in a side-by-side configuration or stacked on top of the IC die. Our MEMS are far more robust than quartz mainly because of their small mass and unlike quartz which is manufactured on an individual crystal basis, our MEMS are assembled on 8 inch wafers with very high density, so our costs are much lower than that of Quartz.

  15. amond
    December 1, 2014

    SachinEE, in 2015 we expect our yields will be in the 90-95% region. obviously our goal is to push this to the high 90's through ongoing process improvements.

  16. amond
    December 1, 2014

    Hi SachinEE, regarding the frequency error vs temperature performance. Today quartz is better than MEMS. AT cut quartz has the typical “wave” shaped curve, while our MEMS is a parabolic curve. This curve is highly repeatable and therefore easy to work with. Over 0 to +60 it is typically +/-40ppm. There are ways to flatten our parabolic curve even more and we plan to have improved stability in the future. That being said for most IoT applications our standard curve is sufficient. Those customers/applications that require tighter stability can take advantage of our on-MEMS sensor which allow the IC manufacture to carry out temperature compensation to levels as low as sub 1ppm over -40 to +85'C

  17. Steve Taranovich
    December 1, 2014

    @amond—thanks for lending your expert answers!

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