Terahertz Electronics

Tuning to Terahertz Electronics

The terahertz (THz) region (nominally 0.1-10THz) separates electronics from photonics, and has historically been difficult to access. Semiconductor electronics run out of steam after ~100GHz due to transport time limitations. Photonic devices falter below ~10THz because photon energy drops to thermal energy. At the high-frequency end, infra-red (IR) optoelectronics cannot operate significantly below 10THz. Since these devices employ photon-electron particle interactions, as photon energy hv decreases below thermal energy kT, the device ceases to operate efficiently unless it is cooled down. This adds significant cost and weight. At the low-frequency end, semiconductor electronic devices cannot operate at frequencies significantly above 100GHz. Transport time across the semiconductor junction is limited by drift and diffusion speeds. The largely-untapped frequency region between 100GHz and 10THz (the THz region) holds promise for a wide range of commercial and military applications. Terahertz electronics (TE) is a new technology that extends the range of electronics into the THz-frequency region.

Terahertz electronics

Terahertz electronics technology opens up practical applications in high-speed data interconnects, THz imaging, and highly-integrated radar and communication systems. The gap between electronics and photonics has closed. Further use and development of such technological devices will make TE a reality in the near future. It does not use semiconductors; instead, it is based on metal-insulator tunnelling structures to form diodes for detectors and ultra-high-speed tunnelling transistors for oscillator based transmitters. With these devices, detectors and transistors for operation in the THz region have been designed. Besides being extremely fast, TE devices are made entirely of thin-film materials—metals and insulators—and so may be fabricated on top of complementary metal oxide semiconductor (CMOS) circuitry—a technology for constructing integrated-circuits circuitry or on a wide variety of substrate materials.

Based on metal-insulator tunnel junctions, TE technology extends the range of electronics beyond the 100GHz barrier to 10THz. In these devices, charge transport through the junction occurs via electron tunnelling, which has a time constant of ~10–15 seconds. Charge transport to and from the junction occurs via plasma oscillation in metals, which is easily supported with low loss in the THz range of interest. Furthermore, epitaxial growth and high process temperatures are not required. Thus, integration of TE onto low-loss insulating substrates (for example, glass, sapphire, ceramic or plastic) or onto silicon-integrated circuits is possible. Industries are employing this concept in practical components, like detectors, transistors, mixers and other devices, to provide a full suite of ultra-fast integrated components for building high-frequency electromagnetic wave circuits and systems. The result is complete integrability, and consequently, low cost. In addition, devices may be fabricated onto large-area flat panels or flexible sheets, enabling completely integrated microwave/millimetre-wave/sub-millimetre-wave sensor and emitter arrays. These devices operate at low voltages, allowing compatibility with CMOS circuitry, coupled with innovations in antenna design and travelling wave devices. This leap in performance and flexibility enables a host of new applications for TE. 

Sources of terahertz radiations

One of the main reasons that THz applications have not fully materialised yet is the lack of a small, low-cost, moderate-power THz source. THz radiations are generally emitted as a part of black-body radiation from anything with temperatures greater than 10 kelvin. While this thermal emission is very weak, observations at these frequencies are important for characterising the cold 10-20K dust in the interstellar medium. However, the opacity of the Earth’s atmosphere to sub-millimetre radiation restricts these observatories to very high altitude sites, or to space. About a decade back the only viable sources of THz radiation were:
1. The gyrotron
2. The backward-wave oscillator (BWO)
3. The far IR laser (FIR laser)
4. Quantum cascade laser
5. The free electron laser (FEL)
6. Synchrotron light sources
7. Photo-mixing sources
8. Single-cycle sources used in THz time domain spectroscopy, such as hoto-conductive, surface field, photo-dember and optical-rectification emitters 

There have also been solid-state sources of millimetre and sub-millimetre waves for many years. Nowadays, most time-domain work is done via ultra-fast lasers. In mid 2007, scientists announced the creation of a compact device that can lead to portable, battery-operated sources of T-rays, or THz radiation. This new T-ray source uses high-temperature superconducting crystals that comprise stacks of Josephson junctions that exhibit a unique electrical property—when an external voltage is applied, an alternating current will flow back and forth across junctions at a frequency proportional to the strength of the voltage (phenomenon known as Josephson effect). These alternating currents then produce electro-magnetic fields whose frequency is tuned by the applied voltage. Even a small voltage, around two millivolts per junction, can induce frequencies in the THz range. 

In 2008, engineers announced they had built a room-temperature semiconductor source of coherent THz radiation. Until then, sources had required cryogenic cooling, greatly limiting their use in everyday applications. 

Many other THz-source technologies have been investigated in the past four decades. Numerous groups worldwide are producing tuneable CW THz radiation using photo-mixing of near-IR lasers. Direct multiplied (DM) sources take millimetre-wave sources and directly multiply their output up to THz frequencies. DM sources with frequencies up to a little more than 1THz and approximately 1µW of output have been used as local oscillators for heterodyne receivers in select applications, most of which are in radio astronomy. 

However, these can produce substantially more output power at lower frequencies, and are often well-suited to applications requiring frequencies of less than 500GHz. In addition, physicists have recently demonstrated quantum-cascade semiconductor lasers operating at wavelengths in the 4.4THz regime. These lasers are made from 1500 alternating layers (or stages) of gallium-arsenide and aluminium-gallium-arsenide and have produced 2mW of peak power (20nW average power), and advances in output power and operating wavelength continue at a rapid pace.

Recently, researchers at JILA (formerly known as Joint Institute for Laboratory Astrophysics), jointly operated by University of Colorado and National Institute of Standards and Technology, USA, have developed a laser based source of THz radiation that is unusually efficient and less prone to damage than similar systems. JILA instruments for generating THz radiation make use of ultra-fast pulses of near-IR laser light that enter through the lens on left, striking a semiconductor wafer studded with electrodes (transparent square that is barely visible under the white box connected to orange wires) bathed in an oscillating electric field. The light dislodges electrons, which accelerate in the electric field and emit waves of THz radiation. Fig. 3 shows the close-up of the electron source.

General applications 

THz radiations are non-ionising, and therefore safe to humans. These penetrate a wide variety of non-conducting materials, including clothing, paper, plastics and ceramics, and can also penetrate fog and clouds, but are strongly absorbed by metal and water. Until recently, researchers did not extensively explore the material interactions occurring in the THz-spectral region because they lacked reliable sources of THz radiation. However, pressure to develop new THz sources arose from two dramatically different groups—ultra-fast time-domain spectroscopists who wanted to work with longer wavelengths, and long-wavelength radio astronomers who wanted to work with shorter wavelengths. Today, with continuous wave (CW) and pulsed sources readily available, investigators are pursuing potential THz-wavelength applications in many fields. 

Companies are planning to exploit the commercial applications of TE. THz applications span the physical (security imaging), biological (cell formation) and medical (cancerous-tumour detection) sciences with a growing interest in the application of THz frequencies from security imaging through clothing in airport scanners to non-destructive pharmaceutical and manufacturing inspection through multilayered or opaque surfaces. The unique properties of THz radiation also include high-frequency radars to produce high-resolution images of objects through cloud, fog and dust storms to support aircraft landing in harsh environments.

Much of the recent interest in THz radiation stems from its ability to penetrate deep into many organic materials without the damage associated with ionising radiation such as X-rays. Also, because THz radiation is readily absorbed by water, it can be used to distinguish between materials with varying water content, for example, fat versus lean meat. These properties lend themselves to applications in process and quality control as well as biomedical imaging. Tests are currently underway to determine whether THz tomographic imaging can augment or replace mammography, and some people have proposed THz imaging as a method of screening passengers for explosives at airports as well as for detecting the presence of cancerous cells in humans. However, all these applications are still in the research phase.

THz radiation can also help scientists understand the complex dynamics involved in condensed-matter physics and processes such as molecular recognition and protein folding. CW THz technology has long interested astronomers because approximately one-half of the total luminosity and 98 per cent of the photons emitted since the Big Bang fall into the sub-millimetre and far-IR, and CW THz sources can be used to help study these photons. One type of CW THz source is the optically pumped THz laser (OPTL). These lasers are in use around the world, primarily for astronomy, environmental monitoring and plasma diagnostics. The emerging field of time-domain spectroscopy (TDS) typically relies on a broadband short-pulse THz source. A split antenna is fabricated on a semiconductor substrate to create a switch. A DC bias is placed across the antenna, and an ultra-short pump-laser pulse (<100fs) is focused in the gap in the antenna. The bias-laser pulse combination allows electrons to rapidly jump the gap, and the resulting current in the antenna produces a THz electromagnetic wave. This radiation is collected and collimated with an appropriate optical system to produce a beam.

Terahertz electronic devices

Metal oxide semiconductor (MOS) transistor is the building block of integrated circuits (ICs) in electronics and is the engine that powers these. Today’s most complex ICs, such as microprocessors, graphics and DSP chips, pack more than 100 million MOS transistors on a single chip. Integration of one billion transistors into a single chip will soon become a reality. The semiconductor industry faces an environment that includes increasing chip complexity, continued cost pressures, increasing environmental regulations and growing concern about energy consumption. The observation that the number of transistors per integrated circuit doubles every 18 to 24 months is well-known to industry analysts and many of the general public. New materials and technologies are needed to support the continuation of Moore’s law. 

TE holds promise of greatly-expanding and numerous applications in detection of biological and chemical hazardous agents, building and airport security, and explosive detection, as well as in radio astronomy, biology and medicine. Many companies are thinking towards exploiting the commercial applications of TE beyond traditional aerospace and medical markets. The technology being exploited depends on the fabrication of electronic devices that operate above 100GHz, where traditional electronic circuits no longer function. It is a generic device technology that can be used as both a detector and source of THz radiation, opening the potential for very-high-frequency communication systems and radars. The devices, Schottky diodes, operate at room temperature, rather than under cryogenic conditions like most competitor technologies, significantly simplifying system infrastructure and reducing cost.Companies are focusing on the development of microwave monolithic integrated circuit (MMIC) technologies at frequencies approaching 1THz, including corresponding circuits, components and modules. Voltage-controlled oscillators and amplifiers, power amplifiers, frequency multipliers and mixers will soon be developed with operating frequencies beyond 500GHz. These devices shall be used to realise compact integrated front-end modules for radar and communication systems.

THz transistor technology is now emerging and short-channel Si CMOS, InGaAs based hetero-structure bipolar transistors and high-electron mobility transistors have reached cut-off frequencies and maximum frequencies of oscillation in the THz range. Si Schottky diodes have demonstrated millimetre-wave detection. GaN based FETs have additional advantages at THz frequencies with a different design. The device feature-sizes have shrunk to the point where ballistic mode of electron transport becomes important or even dominant. THz radiation excites oscillations of the electron density (plasma waves) in transistor channels. Plasma waves propagate with velocities much larger than electron drift velocities and have characteristic frequencies in the THz range even for devices with feature-sizes exceeding a few hundred nanometres. The rectification of plasma waves by the device non-linearity can be used for detecting THz radiation and for imaging and in-situ testing of transistor structures. Using synchronised THz transistor arrays, it is expected to yield dramatic performance improvements of plasmonic THz electronic detectors and sources.
 
Today’s research of TE is also focused on a variety of different compact optoelectronic devices, like photoconductive antennae (PCA), which operate at room temperature but need an external laser excitation, or THz quantum cascade lasers that are powerful but currently operate at cryogenic temperatures. One of the main sources of THz radiation, the inter-digitated photoconductive antenna, can now be tuned to THz frequencies that were previously difficult to reach. Researchers found that changing the spacing between electrodes in the antenna’s structure enables the emission spectrum to be centred at a chosen frequency—a property that will be useful for spectroscopy and imaging, where access to particular parts of the THz spectrum is needed.
 
We will need to think about new geometries and new materials to improve these issues, possibly combined with the use of cheaper and compact fibre based laser systems. Improving these types of sources will permit the THz technological range to become mature and comparable to those used in microwave electronics and IR optical systems.

Challenges ahead

The objective of the TE program is to develop critical devices and integration technologies necessary to realise compact, high-performance electronic circuits that operate at centre frequencies exceeding 1THz. The main focus will be on the development of two critical THz technical areas. One is THz transistor electronics to develop multi-THz InP HBT and InP HEMT transistor technologies to enable TMICs along with THz low-loss inter-element interconnect and integration technologies to build compact THz transmitter and receiver modules. Another is THz high-power amplifier modules for compact, micro-machined vacuum electronics devices to produce a significant increase of output power at frequencies beyond 1THz and to radiate this energy at an antenna.The success of TE will lead to revolutionary applications by enabling coherent THz-processing techniques such as THz-imaging systems, sub-MMW, ultra-wideband, ultra-high-capacity communication links and sub-MMW, single-chip widely-tuneable synthesisers for explosive-detection spectroscopy. Despite intense research efforts, there have been many challenges that have not yet been overcome in achieving a miniature, efficient THz source. Further research in TE should investigate innovative approaches that enable revolutionary advances in electronic devices and ICs achieving THz frequencies. Efforts are being made to use band-gap engineering and the unique properties of graphene to develop basic building blocks of graphene TE and to accelerate its applications.

courtesy:

 Dr S.S. Verma ( professor at Department of Physics, Sand Longowal Institute of Engineering & Technology, Sangrur, Punjab)

FPGA's for The Internet of Things

" Billions of devices are expected to be connected wirelessly by 2020. In this emerging era of connected devices, machines need not only be secure but also need to be secure at device, design and system levels. "

Billions of devices are expected to be connected wirelessly by 2020. In this emerging era of connected devices, machines need not only be secure but also need to be secure at device, design and system levels. The Internet of Things (IoT) requires diverse technology and specialised skill areas such as specialised hardware and sensor development, along with sophisticated real-time embedded firmware, cloud applications and Big Data analytics for massive real-time data into usable information, delivery of data to human-scale and human-usable platforms, particularly sophisticated smartphone apps. The IoT is revealing an important need in technology, that is, programmable hardware and I/O.

The IoT will soon be driven by field-programmable gate array (FPGA)-like devices, because these devices can interface with the outside world very easily and provide lowest power, lowest latency and best determinism. The IoT would interface with temperature, pressure, position, acceleration, analogue-to-digital converters (ADCs), digital-to-analogue converters (DACs), current and voltage, among others. Arduino and Raspberry Pi could also be used.

An FPGA can be considered a programmable special-purpose processor as it can handle signals at its input pins, process these and drive signals on its output pins.

The above system is very deterministic. An FPGA can interact with memory and storage devices through serialiser/deserialiser interfaces (SERDES), which also allow for Ethernet, serial or Bluetooth communication. An FPGA can, for example, take an HTTP request packet received from a wireless Ethernet component, decode its request, fetch information from memory and return the requested result back through the Ethernet device.

The FPGA could be coupled with an ARM processor to leverage higher-level software functions such as Web servers or security packages, if higher level of processing is required. The key consideration is the programmable aspect of an FPGA. In a typical development cycle, a supplier development kit is employed to configure the FPGA, while a printed circuit board (PCB) is developed with specific sensor/communication/display components, as required.

The IoT challenges

The IoT challenges include security, privacy, unauthorised access, malicious control and denial of service. A hardware-first approach with respect to security and implementation of necessary functionality on the systems on chip (SoC) level is vital for fully securing devices and platforms such as FPGAs, wearables, smartphones, tablets and other intelligent appliances.

In practice, the hardware-based platform offers a single user interface (UI) across factory locations, real-time visibility into operations and remote, cloud based feature activation. IoT devices also have long life spans, yet manufacturers are likely to stop developing and rolling out patches for a product once it reaches obsolescence. For these reasons, IoT devices should leverage hardware based security and isolation mechanisms that offer robust protection against various forms of attack.

The outside layer of this network comprises physical devices that touch, or almost touch, the real world, such as sensors (optical, thermal, mechanical and others) that measure the physical states of houses, machines or people.

There are some complete control systems such as thermostats, smartappliances or drone helicopters. The presence of these complex devices introduces an encounter with the IoT in the form of sensors and actuators, or complete systems.

Consider the thermostat at home. When we add an interface to it so that a mobile app can read the temperature, check for failures and change the set-point, it works automatically. This approach wants to, whenever possible, move control onto the Internet, and ideally onto a computing cloud and scatter tiny, inexpensive sensors everywhere. Here, we eliminate the thermostat altogether and, instead, put temperature sensors around the house, inside and out. And while we are at it, we pull the controller boards out of the furnace and air-conditioner, connect their inputs and outputs to the Internet as well, so a cloud application can directly read their states and control their sub-systems.

In general, these wireless interfaces match the characteristics such as low power and the ability to sleep at very low quiescent current, long periods of sleep and short bursts of activity. But the interfaces bring with them baggage, too. These are mutually-incompatible, have a short range and use simplified, non-Internet protocol (IP) packet formats. These characteristics necessitate a new kind of device to intermediate between the capillary network and the next layer of the IoT, that is, a local IoT concentrator.

The concentrator serves as a hub for short-range radio frequency (RF) links in its immediate vicinity, manages the link interfaces and exchanges data with these. Because these concentrators are unlikely to have any direct connection to an Internet-access router, these will generally use Wi-Fi or Long Term Evolution (LTE) as a backhaul network, which then becomes the second layer of the IoT. It is the job of the hub, then, to perform routine work of a network bridge as well as packing and unpacking, shaping traffic and translating between headers used in short-range RF packets and headers necessary for backhaul networks.

Future trends

In future, we can expect vehicles with an increasing amount of autonomous capabilities to navigate roads and highways, and interact with each other, their owners and the IoT. Intelligent cars and smartgrids are just the beginning of a changing ecosystem, where devices, systems and platforms that were previously disconnected will become online.

Ultimately, integration of various IoT devices and platforms will lead to the proliferation of smartcities across the globe, riding on the new digital infrastructure enabled by ubiquitous connectivity and the ever-increasing bandwidth. Thus, it is important to realise that, just because a system is embedded, it does not mean it is secure or will remain so, indefinitely.

Therefore security must be perceived as hardware rather than software patches, with chip makers routinely forced to contend with a wide range of potentially serious threats including data breaches, counterfeit components and intellectual property (IP) theft. Apart from ensuring fundamental chip security during manufacturing, embedding the right security intellectual property (IP) core into an SoC can help manufacturers design devices, platforms and systems that remain secure throughout their respective lifecycles.

Hardware-enabled examples include device provisioning, subscription management, secure payments, authorisation and return merchandise authorisation (RMA)/test support. Embedded SoC security can provide a critical root of trust, managing sensitive keys for secure boot, service authentication and key management. The SoC security core can regulate debug modes to thwart reverse engineering, while providing chip authentication to prevent counterfeiting. SoC based security can also manage one-time programming of on-chip resources.

COURTESY:V.P. Sampath , active member of IEEE and Institution of Engineers India. He is a regular contributor to national newspapers, IEEE-MAS section and has published international papers on VLSI and networks

Flexible Transistors

Flexible transistors could revolutionise the medical and consumer electronics industry, and have a look at some of the interesting applications being prototyped

The wearable electronics industry will soon be booming, according to many technology analysts. But the rigidity of the circuitry that goes inside the gadget has always been a limiting factor for developing devices that can be worn longer without discomfort.

Traditional TFT
Conventional thin-film transistors (TFTs) are rigid components made from inorganic materials such silicon and silicon-based compounds. But, the rigid nature of transistors has been hindering the development of wearables as it does not offer flexibility, consumes high power and causes general discomfort. The manufacturing is also costly because it requires a clean environment, high temperature, and complex, expensive steps of processing.

How organic TFT helps
An organic thin-film transistor (OTFT) uses organic semiconductors in its channel and is preferred in display systems due to its brightness, fast response time, vivid colours and ease of reading in ambient light. These are cheaper, more flexible, cheap and low-maintenance. Moreover, their electronic, chemical, optical and structural properties can be characterised to ease their processing; this can be utilised to coat them on a variety of surfaces, including soft substrates at relatively low temperatures.

Solving carrier mobility and strain effects
Thought OTFTs are relatively cheaper, their carrier mobility (the ease with which an electron can move inside a conductor or semiconductor under the influence of an electric field) is less. This would lead to sluggish response time, affecting the animation or video being displayed. It has been found out that the carrier mobility is influenced by crystallinity and the molecular arrangement in a crystal lattice. Researchers at the University of Nebraska-Lincoln, Stanford University, SLAC National Accelerator Laboratory and Oak Ridge National Laboratory have jointly come up with an off-centre spin-coating method that significantly boosts the carrier mobility of organic crystals.

Another challenge faced by scientists was to understand how the bending of the transistor would affect its performance as mechanical deformation could affect the electrical properties of the transistor, and several studies were being done in this area. A series of experiments by the University of Massachusetts, Amherst, has shown that such mechanical deformations decrease the performance of an OTFT only under certain conditions, and in other instances it either has no effect or enhances the performance of the TFT. They also propose a plate bending theory-based model to quantify the possible strains on the transistor due to deformations, and this would prove helpful for the development of better flexible devices.

Newspaper – Hogwarts style
OTFT technology would aid diverse applications. As already mentioned, they allow the fabrication of displays on flexible surfaces, unlike traditional TFT screens. One could give an OTFT coating to a flexible plastic sheet and it can be turned into a display whose content can be animated or varied periodically. By stacking a few such sheets you could make your own Daily Prophet newspaper, just like the ones in the Harry Potter series! Or you could have the Spider Man in a comic book move around the pages and speak the dialogues. Another possibility is an electronic tattoo to monitor your vital signs, which can be stuck to or removed from your skin just like a temporary tattoo.
Wow, OTFT surely offers myriad interesting possibilities, particularly in the consumer electronics, entertainment and medical fields. Lots to look forward to! 


COURTESY : EFY

Li Fi - Light Fidelity

Li Fi post 2

After success of wireless data transmission technology Wi-Fi, scientists are coming with a new age technology ‪#‎Li_Fi‬.

'#Li_Fi' is a lot faster than what we are currently getting from Wi-Fi. In Lab conditions, researchers claimed to achieve the speeds of 224 gigabits per second by testing #Li_Fi technology.
Researchers believe that #Li_Fi is capable of sending data up to 1GB per second which is 100 times quicker than average Wi-Fi networks.

5 Free eBooks On Analog Circuits Designing

Learn to design and program your own circuits with there free ebooks. Happy reading!

1. Analog Integrated Circuit Design

Author/s: Tony Chan, Carusone David A. Johns, Kenneth W. Martin

Publisher: Wiley

This book strives to quash the notion that the design and test of high-performance analog circuits are “mys-tical arts.” Whereas digital design is relatively systematic, analog design appears to be much more based uponintuition and experience.

2. Analog Circuits

Author/s: Yuping Wu

Publisher: InTech

The invariable motif for analog design is to explore the new circuit topologies, architectures and CAD technologies to overcome the design challenges coming from the new applications and new fabrication technologies. In this book, a new architecture for a SAR ADC is proposed to eliminate the process mismatches and minimize the errors. A collection of DG-MOSFET based analog/RFICs present the excellent performance; the automated system for a passive filter circuits design is presented with the local searching engaging; interval analysis is used to solve some problems for linear and nonlinear analog circuits and a symbolic method is proposed to solve the testability problem.

3. CMOS Circuit Design, Layout, and Simulation (3rd Edition)

Author/s: Phillip E. Allen, Douglas R. Holberg

Publisher: Oxford

The Third Edition of the book covers the practical design of both analog and digital integrated circuits, offering a vital, contemporary view of a wide range of analog/digital circuit blocks including: phase-locked-loops, delta-sigma sensing circuits, voltage/current references, op-amps, the design of data converters, and much more. Regardless of one's integrated circuit (IC) design skill level, this book allows readers to experience both the theory behind, and the hands-on implementation of, complementary metal oxide semiconductor (CMOS) IC design via detailed derivations, discussions, and hundreds of design, layout, and simulation examples.


4. Analog Integrated Circuits for Communication: Principles, Simulation and Design

Author/s: Donald O. Pederson, Kartikeya Mayaram

Publisher: Springer

Analog Integrated Circuits for Communication: Principles, Simulation and Design, Second Edition covers the analysis and design of nonlinear analog integrated circuits that form the basis of present-day communication systems. Both bipolar and MOS transistor circuits are analyzed and several numerical examples are used to illustrate the analysis and design techniques developed in this book. Especially unique to this work is the tight coupling between the first-order circuit analysis and circuit simulation results. Extensive use has been made of the public domain circuit simulator Spice, to verify the results of first-order analyses, and for detailed simulations with complex device models.

5. Analysis and Design of Analog Integrated Circuits

Author/s: Paul R. Gray, Paul J. Hurst, Stephen H. Lewis, Robert G. Meyer

Publisher: Wiley

This is the only comprehensive book in the market for engineers that covers the design of CMOS and bipolar analog integrated circuits. The fifth edition retains its completeness and updates the coverage of bipolar and CMOS circuits.

A thorough analysis of a new low-voltage bipolar operational amplifier has been added to Chapters 6, 7, 9, and 11. Chapter 12 has been updated to include a fully differential folded cascode operational amplifier example. With its streamlined and up-to-date coverage, more engineers will turn to this resource to explore key concepts in the field.

COURTSY : EFY

10 Technologies To Be Thankful For

From wearables and 3D printing to smart home innovations and intelligent transportation, the 2015 tech market has given us lots to be thankful for. To kick off Thanksgiving in the US, we’ve pulled together a top 10 list of gadgets and technologies from the past year that have, or will have, a positive impact on humanity.

1. Supercomputers: Supercomputers have helped us make some great strides in healthcare. For example, teams from UC Berkeley and the University of California San Diego used the supercomputing resources of the National Energy Research Scientific Computing Center to simulate how ultrasounds and tiny bubbles injected into the bloodstream might break up blood clots, limiting the damage caused by a stroke in its first hours.
2. 3D Printing: 3D printing isn’t just millennial makers. In fact, its applications are very promising and ever-evolving across many industries, including healthcare, education, and even fashion. Imagine how much more fun science and math might have been in high school way back when had the charts, graphs and models been 3D printed.
3. Intelligent Transportation: Google is not the only name in the driverless car game. In fact, automakers including Audi, BMW and Volvo have all tossed their hats in the ring to create intelligent transportation solutions, and the ante was upped even more when Apple followed suit.
4. Smart Home Appliances: The smart home landscape continues to take off, with new products emerging often. While lighting remains the gateway product, the possibilities extend to securing and operating every room and appliance in the house.
5. Biometric Authentication: You don’t have to work in finance to know that money is complex, and so securing it goes well beyond a typical text-based password. Biometric authentication for mobile payments will continue to diversify beyond fingerprints to things like facial recognition, and innovations will continue to be a result of partnerships, like the one between Accenture and Visa.
6. Augmented Reality/Virtual Reality (AR/VR): Twenty-first century medicine is far from traditional — everything is laced with technology. AR/VR has offered healthcare professionals alternative options for surgical training, therapy, and even stroke rehabilitation.
7. Artificial Intelligence: Robotics have come a long way since Rosie, the Jetson’s maid. AI has made its mark on education by offering students an opportunity to think critically and creatively in an interactive environment. It has also made an impact in medicine, where nanorobots are used for surgical procedures, search and safety, and food safety.
8. Wearables: Fitness trackers kicked off the wearable fad, but they only scratch the surface of possibility with wearables. The landscape continues to evolve as consumers grow more comfortable interacting with technology that’s less visible. The technology will grow more sophisticated as more data is collected about the user experience across devices.
9. Application-Powered Technology: As tech innovations become more and more invisible, apps to power them become more necessary. Wearables and other IoT devices almost all have companion apps that serve as the main command center, so that if for some reason a rule or setting fails, there’s a main dashboard to update or reset functionality.
10. Data Storage Solutions: Devices aren’t the only technology pressured to change over time. As more devices emerge that collect information, data storage solutions must also change and adapt. We’ve evolved past paper punch cardswith cloud systems dominating the market, housing more than one exabyte (about one quintillion bytes) of data.

courrtsy: IEEE Spectrum TM

MIT's 3-D Microwave Camera Can See Through Walls

See Through Walls - MIT's 3-D Microwave Camera Can See Through Walls

Image: Camera Culture Group/MIT Media Lab

Microwaves propagating across a metal peacock ornament are visualized as a color-coded temporal sequence

Visible light is all well and good for things like eyeballs, but here at IEEE, we do our best to cover the entire spectrum. As always, we’re especially interested in anything that confers superhero-like abilities, like X-ray vision, or in this case, M-wave vision, which sounds even more futuristic. At MIT, they’ve been working on a prototype for a time of flight microwave camerawhich can be used to image objects through walls, in 3-D.

A microwave camera is sort of like a cross between a visible light camera and a radar imaging system, incorporating some of the advantages of each. Like radar, microwaves don’t really notice things like darkness or fog or walls, but unlike radar they’re not confused by the kinds of angled surfaces that make the stealth fighter so stealthy. Radar systems also tend to be big, complex, low resolution, and expensive. By taking a more camera-like approach to radio frequency imaging, essentially treating microwaves like waves of light and using a passive reflector like a lens, MIT has been able to leverage computational-imaging techniques to develop a low cost, high resolution imaging system.

MIT’s microwave camera can do 3-D imaging using time of flight, in the same way that Microsoft’s latest Xbox Kinect sensor works. The time of flight camera sends out bursts of microwaves and then keeps careful track of how long it takes for the microwaves to bounce off of something and return to the sensor. After doing some not very fancy math with the speed of light, you can then calculate how far away that something is. MIT’s camera has a temporal resolution of 200 picoseconds, allowing it to resolve distances with an accuracy of 6 cm, enough for usable 3-D imaging.

Here's a video showing the microwave camera taking pictures of (among other things) a mannequin through a solid wall:

 ,

If the mannequin in the video looks suspiciously like it's covered in aluminum foil, that’s almost certainly because it is, in fact, covered in aluminum foil. Doing this actually makes the mannequin more human like: we’re very good at reflecting microwaves in this frequency range because we’re ugly bags of mostly water, and covering the plastic mannequin in tin foil makes it a close approximation to the real thing. You can see the resolved 3-D image at the tail end of the video, and at 41 x 41 pixels, it’s sufficient resolution “to [be] able to see how many limbs a person has,” according to MIT. You know, just in case whatever is on the other side of the wall has extra limbs, which means you probably don’t want to enter that room.

Images: Camera Culture Group/MIT Media Lab

One other trick that the microwave camera is capable of is multispectral imaging. As the camera takes each measurement, the microwave emitter sweeps through a frequency range of 7.835 GHz to 12.817 GHz over 10 ms (your microwave oven operates at 2.45 GHz). Different materials respond to the microwaves differently at lower and higher frequencies, and the camera can separate out these spectra. This gives you an image with multiple frequency response “colors,” and the patterns of colors that you get provides information about the materials. 

The microwave camera is, at the moment, probably not something that you’d want to carry around. The reflector is over a meter wide, and in order to acquire an image, it has to be mechanically scanned along the entire focal plane, a process that takes something like an hour. However, MIT suggests a few ways of smallerizing the system, including the use of reconfigurable focal-plane sensors or shrinking the transmission wavelength from microwave (3 cm) down to millimeter wave (5 mm), which would significantly reduce the size of the reflector. The idea is that it’ll be useful for the recovery of survivors in disaster situations and imaging in hazardous conditions, which means that it may not be scalable down to cellphone size. Obviously, this is a disappointment for those of us who were looking forward to regularly misusing this kind of technology, as well as those of us who were hoping to have a camera that could also warm up our Hot Pockets.

COURTSY: IEEE SPECTRUM , Evan Ackerman