Category Archives: Applications

Global sales of smartphones to end users totaled 403 million units in the fourth quarter of 2015, a 9.7 percent increase over the same period in 2014, according to Gartner, Inc. However, this was their slowest growth rate since 2008. In 2015 as a whole, smartphone sales reached 1.4 billion units, an increase of 14.4 percent from 2014.

“Low-cost smartphones in emerging markets, and strong demand for premium smartphones, continued to be the driving factors,” said Anshul Gupta, research director at Gartner. “An aggressive pricing from local and Chinese brands in the midrange and entry-level segments of emerging markets led to consumers upgrading more quickly to affordable smartphones.”

Mr. Gupta said that 85 percent of users in the emerging Asia/Pacific market are replacing their current midrange phone with the same category of phone. In addition, currency devaluations against the U.S. dollar in many emerging markets are putting further margin pressure on many vendors that import devices. Current market conditions are prompting some vendors to consider setting up manufacturing operations in India and Indonesia to avoid being hit by future unfavorable currency devaluations and high import taxes.

In the fourth quarter of 2015, Samsung and Huawei were the only two top-five smartphone vendors to increase their sales to end users (see Table 1). Apple suffered its first decline in sales of smartphones — iPhone sales were down 4.4 percent.

Table 1

Worldwide Smartphone Sales to End Users by Vendor in 4Q15 (Thousands of Units)

Company

4Q15

Units

4Q15 Market Share (%)

4Q14

Units

4Q14 Market Share (%)
Samsung

83,437.7

20.7

73,031.5

19.9
Apple

71,525.9

17.7

74,831.7

20.4
Huawei

32,116.5

8.0

21,038.1

5.7
Lenovo*

20,014.7

5.0

24,299.9

6.6
Xiaomi

18,216.6

4.5

18,581.6

5.1
Others

177,798.0

44.1

155,551.6

42.3
Total

403,109.4

100.0

367,334.4

100.0

*The figures for Lenovo include sales of mobile phones by both Lenovo and Motorola

Source: Gartner (February 2016) 

Although Samsung was the No.1 vendor, Gartner analysts said the company faces challenges. “For Samsung to stop falling sales of premium smartphones, it needs to introduce new flagship smartphones that can compete with iPhones and stop the churn to iOS devices,” said Mr. Gupta.

With an increase in sales of 53 percent in the fourth quarter of 2015, Huawei achieved the best performance year over year. Huawei’s increased brand visibility overseas, and its decision to sell almost only smartphones, gave it a higher average selling price in 2015.

For total sales of smartphones in 2015, Samsung maintained the No. 1 position, but its market share declined by 2.2 percentage points (see Table 2). In 2015, Apple sold 225.9 million iPhones, to achieve a market share of almost 16 percent. Huawei’s smartphone sales approached 104 million units, up 53 percent year over year.

Table 2

Worldwide Smartphone Sales to End Users by Vendor in 2015 (Thousands of Units)

Company

2015

Units

2015 Market Share (%)

2014

Units

2014 Market Share (%)
Samsung

320,219.7

22.5

307,596.9

24.7
Apple

225,850.6

15.9

191,425.8

15.4
Huawei

104,094.7

7.3

68,080.7

5.5
Lenovo*

72,748.2

5.1

81,415.8

6.5
Xiaomi

65,618.6

4.6

56,529.3

4.5
Others

635,368.5

44.6

539,691.3

43.4
Total

1,423,900.3

100.0

1,244,739.8

100.0

*The figures for Lenovo include sales of mobile phones by both Lenovo and Motorola

Source: Gartner (February 2016) 

In terms of smartphone operating system (OS) market, Android increased 16.6 percent in the fourth quarter of 2015, to account for 80.7 percent of the global total (see Table 3). “Android benefited from continued demand for affordable smartphones and from the slowdown of iOS units in the premium market in the fourth quarter of 2015,” said Roberta Cozza, research director at Gartner. In the premium segment, despite Apple’s slower year-over-year fourth-quarter sales, Apple narrowed the market share gap with Samsung in 2015 as a whole. 

Table 3

Worldwide Smartphone Sales to End Users by Operating System in 4Q15 (Thousands of Units)

Operating System

4Q15

Units

4Q15 Market Share (%)

4Q14

Units

4Q14 Market Share (%)
Android

325,394.4

80.7

279,057.5

76.0
iOS

71,525.9

17.7

74,831.7

20.4
Windows

4,395.0

1.1

10,424.5

2.8
Blackberry

906.9

0.2

1,733.9

0.5
Others

887.3

0.2

1,286.9

0.4
Total

403,109.4

100.0

367,334.4

100.0

Source: Gartner (February 2016) 

Nanoelectronics research center, imec, and digital research and incubation center, iMinds, today announced that its respective board of directors have approved the intention to merge the research centers. Using the imec name, the combined entities intend to create a high-tech research center for the digital economy. The transaction is expected to be completed by the end of 2016, with the united organization staged to bring added value to existing partners while further strengthening Flanders’ authority as a technology epicenter and region focused on creating a sustainable digital future.

iMinds will be integrated as an additional business unit within imec, resulting in a new research center that will fuse the technology and systems expertise of more than 2,500 imec researchers worldwide with the digital competencies of some 1,000 iMinds researchers representing nearly 50 nationalities. The additions of iMinds’ flagship open innovation research model -ICON- (in which academic researchers and industry partners jointly develop solutions for specific market needs), iStart entrepreneurship program (supporting start-up businesses), and Living Labs will strengthen the unique capabilities and assets of imec as a research and development center.

Imec has been a global leader in the domain of nanoelectronics for more than 30 years, and has innovated applications in smart systems for the Internet of Things (IoT), Internet of Health, and Internet of Power. It has built an extensive and worldwide partner network, as well as in Flanders, and has generated successful spin-offs. iMinds’ activities span research domains such as the IoT, digital privacy and security, and the conversion of raw data into knowledge. Its software expertise is widely renowned and its entrepreneurship activities in Flanders are first-rate.

“The proliferation of the Internet of Everything has created a need for solutions that integrate both hardware and software. Such innovative products that optimally serve tomorrow’s digital economy can only be developed through intense interaction between both worlds. There are infinite opportunities in domains such as sustainable healthcare, smart cities, smart manufacturing, smart finances, smart mobility, smart grids, or in short, smart everything. Research centers such as imec, with its widely acclaimed hardware expertise, and iMinds, an expert in software and ICT applications, are uniquely positioned to bring these concepts to life,” stated Luc Van den hove, president and CEO of imec. “Furthermore, iMinds is widely recognized for its business incubation programs and open access to SMEs, and, this merger provides us with a unique opportunity to jointly reach out to the Flemish industry and further elevate Smart Flanders on the global map.”

“Flanders faces the enormous challenge of realizing a successful transition towards tomorrow’s digital society; a transition that must happen quickly, considering the urgency to reinforce Flanders’ industrial position,” commented Danny Goderis, CEO of iMinds. “The merger between imec and iMinds is Flanders’ answer to this rapidly accelerating digitization trend. We have a clear ambition to pair more than 3,500 top researchers across 70 countries with an ecosystem of Flemish companies and start-ups, thereby significantly increasing our economic and societal impact. Together, we can help Flanders boost its competitiveness and claim a strong international position.”

Now that the intention to merge has been approved, the merger protocol will be developed and the integration process of imec and iMinds will be initiated immediately. The current iMinds activities will constitute a third pillar next to imec’s units. iMinds will remain headquartered in Ghent with its researchers spread across the Flemish universities. The ambition is to operate as one organization by the end of 2016.

Flemish Minister of Innovation Philippe Muyters welcomes the fact that iMinds and imec join forces: “Thanks to their pioneering work in their respective fields, they have put themselves on the world map. When they were founded, the line between hardware and software was still very clear. Today, and especially in the future, this line is increasingly blurring – with technology, systems and applications being developed in close conjunction. The merger anticipates this trend and creates a high-tech research center for the digital economy that keeps Flanders on the world map. The gradual integration of both research centers, and the agreement to preserve their respective strengths and uniqueness, will make for a bright future.”

Today, at the 2016 Mobile World Congress, Bosch Sensortec introduces its first generation of sensor hub products with optimized vital sensing features. These devices fuse photoplethysmography (PPG) signals with the onboard inertial MEMS sensors signals for robust, motion compensated heart rate measurement and provide users with valuable insights about their wellbeing and fitness level using Firstbeat’s field-proven vital analytics algorithms.

Vital analytics for an enhanced user experience

These new BHV250 and BHV160 sensors are designed for always-on sensor enabled wearable applications such as fitness wristbands, earphones and smart textiles. As a complete sensor solution they feature ultra-low power consumption in a compact package, with integrated software and a wide-range support for different PPG chipsets. The integrated software from Firstbeat processes raw sensor data to open up a world of motion-compensated vital monitoring, activity recognition applications and gesture based user interfaces.

The unique combination of the Bosch’s Vital Sensor Hubs with Firstbeat’s extensive vital analytics software enables a rich user experience by providing the tools for sleep analysis, calorie consumption calculation, fitness training evaluation, and “stress and recovery” monitoring. The myriad of future applications is only limited by the designer’s imagination.

“With this all-round sensor subsystem, our customers can now focus on providing added value to their end users, confident in the knowledge that they have a highly integrated, ultra-low power solution”, said Jeanne Forget-Funk, VP Marketing at Bosch Sensortec. “With the fitness tracking and wearables markets expanding so rapidly, we await with great interest the explosion of innovation that will be triggered by this technology.”

“Firstbeat’s analytics software creates a digital model of a user’s physiology through advanced modeling of heart function and heart rate variability (HRV)”, said Joni Kettunen, CEO and Co-founder of Firstbeat. “The Bosch sensor subsystem provides the accurate data and flexible programmability that enables our software to deliver new insights to users at ultra-low power consumption.”

Product details

The BHV250 and BHV160 integrate innovative 3- respectively 6-axis inertial MEMS sensors designed around the new Bosch Sensortec DSP ‘Fuser Core’ powering Firstbeat’s vital analytics software. Both devices include an accelerometer, and the BHV160 also includes a gyroscope.

The Android Wear-compatible sensor hubs are the components with the lowest power consumption available on the market today, helping to significantly extend system battery life time. 

The sensor hubs have tiny footprints that are indispensable for applications where space is tight. The BHV160 measures 3 x 3 x 0.95 mm3, while the BHV250 only a mere 2.2 x 2.2 x 0.95 mm3.

Samples are available today to qualified customers. Mass production is ramping up in Q2 2016. For pricing, please contact Bosch Sensortec.

Market forecast

According to industry analysts, wearables are a market of increasing importance. IDC predicts that by 2019, total shipments in the wearables market will reach some 214 million units.

Nanoelectronics research center imec and Vrije Universiteit Brussel (VUB) present a frequency division duplex (FDD) balance network, capable of dual-frequency impedance tuning for all LTE bands in the 0.7-to-1GHz range. When integrated into an electrical-balance duplexer (EBD), it enables FDD duplexing with antennas in real-world environments, paving the way to high-performance, low-power, low-cost solutions for mobile communication.

An electrical balance duplexer is a tunable RF front-end concept that seeks to address several key challenges of 4G and 5G mobile systems. It balances an on-chip tunable impedance, the so-called balance network, with the antenna impedance, to provide transmit-to-receive (TX-to-RX) isolation and avoid unwanted frequency components in the received signal. It is a promising alternative to the fixed frequency surface-acoustic wave (SAW) filters implemented in today’s mobile phones as more and more SAW duplexers would be needed to support the ever growing amount of bands adopted by operators, increasing size and cost of these devices. Unlike filter-based front-ends, electrical-balance duplexers provide signal cancellation, which could help enable in-band full-duplex for double capacity and increased network density, among other benefits, for next-generation standards.

Imec and VUB’s dual-frequency balance network is the first FDD balance network that allows balancing the on-chip tunable impedance profile with the impedance profile of an antenna at two frequencies, simultaneously. This is crucial, because in real-world situations, the frequency-dependent impedance of an antenna varies over environmental conditions and limits the achievable isolation bandwidth. The balance network can generate, for any LTE band within 0.7-1GHz, a simultaneous transmit-frequency impedance and receive-frequency impedance to provide high TX-to-RX isolation at both frequencies. It is fabricated in a 0.18µm partially depleted RF SOI CMOS technology, which allows it to better withstand the large voltages present in the EBD during full-power TX operation. The active area of the balance network, which consists of 19 switched capacitors and 10 inductors, is 8.28mm2. The balance network is tuned by an in-house developed custom algorithm, which can optimize the tuning codes of all 19 capacitor banks using only the isolation at the TX and RX frequencies as input.

These results were presented at this month’s IEEE International Solid-State Circuits Conference (ISSCC2016). Imec is present at Mobile World Congress 2016 (February 22-26, 2016, Flanders Investment & Trade booth, Hall 7, G71) to showcase its 5G radio technology, mm-wave communication and sensing, ultra-low power radio, sensors and IoT networks, wearable technologies for health, and IC design services.

imec chip

Imagine a hand-held environmental sensor that can instantly test water for lead, E. coli, and pesticides all at the same time, or a biosensor that can perform a complete blood workup from just a single drop. That’s the promise of nanoscale plasmonic interferometry, a technique that combines nanotechnology with plasmonics–the interaction between electrons in a metal and light.

Now researchers from Brown University’s School of Engineering have made an important fundamental advance that could make such devices more practical. The research team has developed a technique that eliminates the need for highly specialized external light sources that deliver coherent light, which the technique normally requires. The advance could enable more versatile and more compact devices.

Plasmonic interferometers that have light emitters within them could make for better, more compact biosensors. Credit: Pacifici Lab / Brown University

Plasmonic interferometers that have light emitters within them could make for better, more compact biosensors. Credit: Pacifici Lab / Brown University

“It has always been assumed that coherent light was necessary for plasmonic interferometry,” said Domenico Pacifici, a professor of engineering who oversaw the work with his postdoctoral researcher Dongfang Li, and graduate student Jing Feng. “But we were able to disprove that assumption.”

Plasmonic interferometers make use of the interaction between light and surface plasmon polaritons, density waves created when light energy rattles free electrons in a metal. One type of interferometer looks like a bull’s-eye structure etched into a thin layer of metal. In the center is a hole poked through the metal layer with a diameter of about 300 nanometers–about 1,000 times smaller than the diameter of a human hair. The hole is encircled by a series of etched grooves, with diameters of a few micrometers. Thousands of these bulls-eyes can be placed on a chip the size of a fingernail.

When light from an external source is shown onto the surface of an interferometer, some of the photons go through the central hole, while others are scattered by the grooves. Those scattered photons generate surface plasmons that propagate through the metal inward toward the hole, where they interact with photons passing through the hole. That creates an interference pattern in the light emitted from the hole, which can be recorded by a detector beneath the metal surface.

When a liquid is deposited on top of an interferometer, the light and the surface plasmons propagate through that liquid before they interfere with each other. That alters the interference patterns picked up by the detector depending on the chemical makeup of the liquid or compounds present in it. By using different sizes of groove rings around the hole, the interferometers can be tuned to detect the signature of specific compounds or molecules. With the ability to put many differently tuned interferometers on one chip, engineers can hypothetically make a versatile detector.

Up to now, all plasmonic interferometers have required the use of highly specialized external light sources that can deliver coherent light–beams in which light waves are parallel, have the same wavelength, and travel in-phase (meaning the peaks and valleys of the waves are aligned). Without coherent light sources, the interferometers cannot produce usable interference patterns. Those kinds of light sources, however, tend to be bulky, expensive, and require careful alignment and periodic recalibration to obtain a reliable optical response.

But Pacifici and his group have come up with a way to eliminate the need for external coherent light. In the new method, fluorescent light-emitting atoms are integrated directly within the tiny hole in the center of the interferometer. An external light source is still necessary to excite the internal emitters, but it need not be a specialized coherent source.

“This is a whole new concept for optical interferometry,” Pacifici said, “an entirely new device.”

In this new device, incoherent light shown on the interferometer causes the fluorescent atoms inside the center hole to generate surface plasmons. Those plasmons propagate outward from the hole, bounce off the groove rings, and propagate back toward the hole after. Once a plasmon propagates back, it interacts with the atom that released it, causing an interference with the directly transmitted photon. Because the emission of a photon and the generation of a plasmon are indistinguishable, alternative paths originating from the same emitter, the process is naturally coherent and interference can therefore occur even though the emitters are excited incoherently.

“The important thing here is that this is a self-interference process,” Pacifici said. “It doesn’t matter that you’re using incoherent light to excite the emitters, you still get a coherent process.”

In addition to eliminating the need for specialized external light sources, the approach has several advantages, Pacifici said. Because the surface plasmons travel out from the hole and back again, they probe the sample on top of the interferometer surface twice. That makes the device more sensitive.

But that’s not the only advantage. In the new device, external light can be projected from underneath the metal surface containing the interferometers instead of from above. That eliminates the need for complex illumination architectures on top of the sensing surface, which could make for easier integration into compact devices.

The embedded light emitters also eliminate the need to control the amount of sample liquid deposited on the interferometer’s surface. Large droplets of liquid can cause lensing effects, a bending of light that can scramble the results from the interferometer. Most plasmonic sensors make use of tiny microfluidic channels to deliver a thin film of liquid to avoid lensing problems. But with internal light emitters excited from the bottom surface, the external light never comes in contact with the sample, so lensing effects are negated, as is the need for microfluidics.

Finally, the internal emitters produce a low intensity light. That’s good for probing delicate samples, such as proteins, than can be damaged by high-intensity light.

More work is required to get the system out of the lab and into devices, and Pacifici and his team plan to continue to refine the idea. The next step will be to try eliminating the external light source altogether. It might be possible, the researchers say, to eventually excite the internal emitters using tiny fiber optic lines, or perhaps electric current.

Still, this initial proof-of-concept is promising, Pacifici said.

“From a fundamental standpoint, we think this new device represents a significant step forward,” he said, “a first demonstration of plasmonic interferometry with incoherent light.”

Mobile Experts released a new report today on Wi-Fi Semiconductors, highlighting the trends in combo chips, SoCs, power amplifiers, LNAs, switches, and Front End Modules (FEMs).  The report covers both access point hardware and client devices, with detailed information regarding the trends to higher levels of integration, higher level MIMO, new standards, and changes in semiconductor process technologies.

Principal Analyst Joe Madden explained, “The market for Wi-Fi semiconductors has been around for many years, but it’s heading into a major growth phase.   More than 77% of mobile traffic actually moves over Wi-Fi, so the Wi-Fi semiconductor market has doubled in size over the past four years.   It will double again by 2020.”

“Several factors are driving massive growth in Wi-Fi semiconductors.   Wi-Fi is migrating to dual-band operation, with MIMO growing steadily in client devices and APs.  The standards are moving to higher functionality, with wider channels and higher order modulation, driving more difficult power amplifier specifications.   At the same time, new IoT devices are emerging with unique requirements in terms of cost, power efficiency, and performance.”

Mr. Madden continued, “As usual, Mobile Experts dove deeply into the RF technology here, and we have determined the direction for GaAs and RF SOI devices, as well as the direction of integration trends for RF devices.”

This report includes 36 charts and diagrams to illustrate both technical and financial analysis for Wi-Fi semiconductors.  A five-year forecast is included for shipments and revenue, related to AP SOCs, AP RF modules, client “combo chips”, client RF modules, and IoT devices.  The document reports on market share for APs, SoCs, and RF devices.

At this week’s SPIE Photonics West, imec will present a new set of hyperspectral sensor and camera solutions with extended spectral range, going from the visible light (VIS) up to near infrared (NIR). The new line-scan VNIR (visible to near-infrared) sensor and snapshot mosaic VNIR camera outperform current solutions in spectral range and compactness.

Example applications for the line-scan sensor are machine vision and remote sensing applications, e .g. precision agriculture using UAVs and satellites. It features 140+bands in the 470-900nm range. Its small form factor is the result of extreme integration of the hyperspectral filter onto the CMOS sensor.

Imec’s 450-875nm snapshot dual-sensor camera targets applications where dynamc effects are imaged: especially medical, machine vision and security surveillance. By integrating, within one single unified dual-sensor camera architecture, a 16-bands 4×4 mosaic sensor covering the 450-600nm range together with a 25-bands 5×5 mosaic sensor covering the 600-875nm range, imec realized a solution that covers a broad spectral range from visible to near-infrared while maintaining high spatial and spectral resolution tradeoffs.

“Working closely with two of our camera partners, VRmagic and Cubert Gmbh, we have realized one of the most advanced snapshot hyperspectral imaging cameras. It captures 40+ bands ranging from 450-875 m, at video-rate speed acquisition. This achievement clearly sets a new milestone for the real-time snapshot hyperspectral imaging camera market;” explains Jerome Baron, business development manager integrated imaging at imec.

Imec’s new line-scan (visible to near infrared) VNIR sensor and snapshot mosaic VNIR camera will be demonstrated at Booth 4144 at SPIE Photonic West exhibition and will be available for early sampling to strategic partners from April 2016.

Renesas Electronics Corp. reported the development of 90-nanometer (nm) one-transistor MONOS (1T-MONOS) flash memory technology that can be used in combination with a variety of processes, such as CMOS and bipolar CMOS DMOS (BiCDMOS), and provides high program/erase (P/E) endurance and low rewrite energy consumption.

Renesas said that it anticipates that the new flash memory circuit technology will enable it to add flash memory to automotive analog devices with improved performance and reliability.
In a release, the Company noted that this circuit technology makes possible the industry’s first P/E endurance of over 100 million cycles under a high junction temperature (Tj) (Note 2) 175 degrees C, while also delivering low rewrite energy of 0.07 mJ/8 KB (millijoule: one thousandth of a joule) for low energy consumption.

Renesas reported that the newly developed flash memory technology restrains additional process costs while providing an easy way to add flash memory to automotive analog and power devices. This means that analog circuits for connecting sensors and motors can employ devices that mix microcontroller (MCU) logic and flash memory based on the new technology. It has the potential to substantially reduce the number of chips used in motor control systems, while helping to make them more compact, lightweight, and power efficient.

Additionally, the new flash memory technology achieves over 100 million P/E cycles, making it suitable for applications such as automatic calibration or status recording using high-frequency sampling under actual usage conditions in the field.

Renesas Electronics Corp. is a supplier of microcontrollers.

The road to more versatile wearable technology is dotted with iron. Specifically, quantum dots of iron arranged on boron nitride nanotubes (BNNTs). The new material is the subject of a study to be published in Scientific Reports later this week, led by Yoke Khin Yap, a professor of physics at Michigan Technological University.

Yap says the iron-studded BNNTs are pushing the boundaries of electronics hardware. The transistors modulating electron flow need an upgrade.

“Look beyond semiconductors,” he says, explaining that materials like silicon semiconductors tend to overheat, can only get so small and leak electric current.

The key to revamping the fundamental base of transistors is creating a series of stepping-stones that use quantum tunneling.

The nanotubes are the mainframe of this new material. BNNTs are great insulators and terrible at conducting electricity. While at first that seems like an odd choice for electronics, the insulating effect of BNNTs is crucial to prevent current leakage and overheating. Additionally, electron flow will only occur across the metal dots on the BNNTs.

In past research, Yap and his team used gold for quantum dots, placed along a BNNT in a tidy line. With enough energy potential, the electrons are repelled by the insulating BNNT and hopscotch from gold dot to gold dot. This electron movement is called quantum tunneling.

“Imagine this as a river, and there’s no bridge; it’s too big to hop over,” Yap says. “Now, picture having stepping stones across the river–you can cross over, but only when you have enough energy to do so.”

Unlike with semiconductors, there is no classical resistance with quantum tunneling. No resistance means no heat. Plus, these materials are very small; the nanomaterials enable the transistors to shrink as well. An added bonus is that BNNTs are also quite flexible, a boon for wearable electronics.

Researchers at MIT and Texas Instruments have developed a new type of radio frequency identification (RFID) chip that is virtually impossible to hack.

If such chips were widely adopted, it could mean that an identity thief couldn’t steal your credit card number or key card information by sitting next to you at a café, and high-tech burglars couldn’t swipe expensive goods from a warehouse and replace them with dummy tags.

Texas Instruments has built several prototypes of the new chip, to the researchers’ specifications, and in experiments the chips have behaved as expected. The researchers presented their research this week at the International Solid-State Circuits Conference, in San Francisco.

According to Chiraag Juvekar, a graduate student in electrical engineering at MIT and first author on the new paper, the chip is designed to prevent so-called side-channel attacks. Side-channel attacks analyze patterns of memory access or fluctuations in power usage when a device is performing a cryptographic operation, in order to extract its cryptographic key.

“The idea in a side-channel attack is that a given execution of the cryptographic algorithm only leaks a slight amount of information,” Juvekar says. “So you need to execute the cryptographic algorithm with the same secret many, many times to get enough leakage to extract a complete secret.”

One way to thwart side-channel attacks is to regularly change secret keys. In that case, the RFID chip would run a random-number generator that would spit out a new secret key after each transaction. A central server would run the same generator, and every time an RFID scanner queried the tag, it would relay the results to the server, to see if the current key was valid.

Blackout

Such a system would still, however, be vulnerable to a “power glitch” attack, in which the RFID chip’s power would be repeatedly cut right before it changed its secret key. An attacker could then run the same side-channel attack thousands of times, with the same key. Power-glitch attacks have been used to circumvent limits on the number of incorrect password entries in password-protected devices, but RFID tags are particularly vulnerable to them, since they’re charged by tag readers and have no onboard power supplies.

Two design innovations allow the MIT researchers’ chip to thwart power-glitch attacks: One is an on-chip power supply whose connection to the chip circuitry would be virtually impossible to cut, and the other is a set of “nonvolatile” memory cells that can store whatever data the chip is working on when it begins to lose power.

For both of these features, the researchers — Juvekar; Anantha Chandrakasan, who is Juvekar’s advisor and the Vannevar Bush Professor of Electrical Engineering and Computer Science; Hyung-Min Lee, who was a postdoc in Chandrakasan’s group when the work was done and is now at IBM; and TI’s Joyce Kwong, who did her master’s degree and PhD with Chandrakasan — use a special type of material known as a ferroelectric crystals.

As a crystal, a ferroelectric material consists of molecules arranged into a regular three-dimensional lattice. In every cell of the lattice, positive and negative charges naturally separate, producing electrical polarization. The application of an electric field, however, can align the cells’ polarization in either of two directions, which can represent the two possible values of a bit of information.

When the electric field is removed, the cells maintain their polarization. Texas Instruments and other chip manufacturers have been using ferroelectric materials to produce nonvolatile memory, or computer memory that retains data when it’s powered off.

Complementary capacitors

A ferroelectric crystal can also be thought of as a capacitor, an electrical component that separates charges and is characterized by the voltage between its negative and positive poles. Texas Instruments’ manufacturing process can produce ferroelectric cells with either of two voltages: 1.5 volts or 3.3 volts.

The researchers’ new chip uses a bank of 3.3-volt capacitors as an on-chip energy source. But it also features 571 1.5-volt cells that are discretely integrated into the chip’s circuitry. When the chip’s power source — the external scanner — is removed, the chip taps the 3.3-volt capacitors and completes as many operations as it can, then stores the data it’s working on in the 1.5-volt cells.

When power returns, before doing anything else the chip recharges the 3.3-volt capacitors, so that if it’s interrupted again, it will have enough power to store data. Then it resumes its previous computation. If that computation was an update of the secret key, it will complete the update before responding to a query from the scanner. Power-glitch attacks won’t work.

Because the chip has to charge capacitors and complete computations every time it powers on, it’s somewhat slower than conventional RFID chips. But in tests, the researchers found that they could get readouts from their chips at a rate of 30 per second, which should be more than fast enough for most RFID applications.