WORLD OF ELECTRONICS

Tele-Graffiti

2011-01-09T15:12:00.000+05:30

Tele-graffiti is a technology that allows two or more users to communicate remotely via hand-drawn sketches. What one person writes at one site is captured by a video camera, transmitted to the other site and displayed there using an LCD projector.
The system was developed at Robotics Institute of Carnegie Mellon university, Pittsburg. The system comprises of a digital camera, a high resolution LCD projector to project the received image, a mirror to reflect the projected image onto the paper, fixture to hold these devices in position and a writing pad to fix the sheet of paper on the top of the table at every station.
The user can write on a regular piece of paper with a pen at his desk. The sketch or writing on the paper is captured by the camera and transmits the digitized image to the receiving end through a data link.
The image can be transmitted over the internet or local area network. The software architecture of system runs on Linux and has four threads the drawing thread, the paper tracking thread, sending thread and receiving thread.
Tele-graffiti has various applications. It can play an important role in remote education and remote designing.
It can also serve as a substitute for internet chat. The advantage of the system is that non-computer people can use it. .

Power over Ethernet (PoE)

2011-01-09T15:08:00.001+05:30

Power over Ethernet (PoE) is a revolutionarytechnology that extends the already ultra-broad functionality of Ethernet by supplying reliable DC power over the same twisted-pair cable that currently carries Ethernet data.
PoE, modeled after the technology used by the telecommunications industry to supply reliable power to telephones, enables lifeline quality power for IP telephones (VoIP) as well as many other low power Ethernet network devices like wireless access points (WAP) and security cameras.
When locating access points, system designers often use the availability of AC (alternating current) electrical outlets to base decisions on where to install access points. In some cases, companies only locate access points near AC outlets and within reach of a typical six foot electrical cord.
Or, they'll look for a convenient location to install new outlets at points where it's suitable to run conduit and mount outlet boxes. All of these situations limit the location of access points and can incur significant costs if new outlets must be installed.
Power-over-Ethernet (PoE) solves these problems. A PoE solution only requires technicians to run one Ethernet cable to the access point for supplying both power and data.
With PoE, power-sourcing equipment detects the presence of an appropriate "powered device" (e.g., an access point or Ethernet hub) and injects applicable current into the data cable.
An access point can operate solely from the power it receives through the data cable.

Subversion

2011-01-09T15:04:00.000+05:30

Engineering revision control developed from formalized processes based on tracking revisions of early blueprints or bluelines. Implicit in this control was the option to be able to return to any earlier state of the design, for cases in which an engineering dead-end was reached in iterating any particular engineering design.
Likewise, in computer software engineering, revision control is any practice which tracks and provides controls over changes to source code. Software developers sometimes use revision control software to maintain documentation and configuration files as well as source code.
In theory, revision control can be applied to any type of information record. In practice, however, the more sophisticated techniques and tools for revision control have rarely been used outside software development circles (though they could actually be of benefit in many other areas).
However, they are beginning to be used for the electronic tracking of changes to CAD files, supplanting the "manual" electronic implementation of traditional revision control.
As software is developed and deployed, it is extremely common for multiple versions of the same software to be deployed in different sites, and for the software's developers to be working privately on updates. Bugs and other issues with software are often only present in certain
versions (because of the fixing of some problems and the introduction of others as the program evolves).
Therefore, for the purposes of locating and fixing bugs, it is vitally important for the debugger to be able to retrieve and run different versions of the software to determine in which version(s) the problem occurs.
It may also be necessary to develop two versions of the software concurrently (for instance, where one version has bugs fixed, but no new features, while the other version is where new features are worked on).
At the simplest level, developers can simply retain multiple copies of the different versions of the program, and number them appropriately. This simple approach has been used on many large software projects.
Whilst this method can work, it is inefficient (as many near-identical copies of the program will be kept around), requires a lot of self-discipline on the part of developers, and often leads to mistakes.
Consequently, systems to automate some or all of the revision control process have been developed.

Fluid Focus Lens

2011-01-09T14:58:00.000+05:30

The camera phone is one of the hottest-selling items in all of consumer electronics. The little gadgets have become so ubiquitous that hardly anyone finds it odd anymore to see tourists squinting with one eye while pointing their cell phones at a Buddhist temple, a Greek statue, or a New York City skyscraper.
It's easy to see why analysts expect that camera phones will outsell conventional digital cameras and traditional film cameras combined.

But as anyone who has ever seen them can attest, the images that come out of camera phones leave plenty to be desired. Part of the problem is their CMOS imaging chips, which typically have a sensor array of only about one mega pixel—a half or less of the number in a low-end digital camera.
When they are, however, the only thing we may see more clearly is the other weakness of these cameras: their tiny, fixed-focus lenses, which have poor light-gathering and resolving power.

Here is a solution. It's modeled on the human eye, with its remarkable optical capabilities. It is called the FluidFocus lens. Like the lens of the eye, this lens, which we built at Philips Research Laboratories, in Eindhoven, the Netherlands, varies its focus by changing shape rather than by changing the relative positions of multiple lenses, as high-quality camera lenses do.
The tests of a prototype FluidFocus lens showed that it can be made nearly as small as a fixed-focus lens. Fixed-focus lenses use a small aperture and short focal length to keep most things in focus, but at the sacrifice of light-gathering power and therefore of picture quality.

At the same time, the prototype lens delivered sharpness that is easily on a par with that of variable-focus lenses. In fact, the optical quality of a liquid lens combined with a good imaging chip could soon give cell phone snapshots quality that rivals images from conventional- and much bulkier- digital cameras.

Silicon Photonics

2011-01-09T14:52:00.000+05:30

Silicon photonics can be defined as the utilization of silicon-based materials for the generation (electrical-to-optical conversion), guidance, control, and detection (optical-to-electrical conversion) of light to communicate information over distance.
The most advanced extension of this concept is to have a comprehensive set of optical and electronic functions available to the designer as monolithically integrated building blocks upon a single silicon substrate.

Within the range of fibre optic telecommunication wavelength (1.3 µm to 1.6 µm), silicon is nearly transparent and generally does not interact with the light, making it an exceptional medium for guiding optical data streams between active components.
But no practical modification to silicon has yet been conceived which gives efficient generation of light. Thus it required the light source as an external component which was a drawback.

There are two parallel approaches being pursued for achieving opto-electronic integration in silicon. The first is to look for specific cases where close integration of an optical component and an electronic circuit can improve overall system performance.
One such case would be to integrate a SiGe photodetector with a Complementary Metal-Oxide-Semiconductor (CMOS) transimpedance amplifier. The second is to achieve a high level of photonic integration with the goal of maximizing the level of optical functionality and optical performance.
This is possible by increasing light emitting efficiency if silicon. The paper basically deals with this aspect.

Embedded DRAM

2011-01-09T14:47:00.000+05:30

his paper examines some aspects of the architecture of embedded DRAM (dynamic random access memory), its applications and its advantages over other conventional memory types.
Embedded DRAM (eDRAM) – the concept of merging DRAM with logic on a single device – has become increasingly popular, thanks to the growth of existing and emerging high bandwidth applications such as graphics processing, backbone and access router data communications systems and base stations for mobile phones.
A common requirement of all these designs is that they have to process very large amounts of data at very high speeds. Because of this, a fundamental design requirement is the ability to provide high performance, high speed memory access.
One way of achieving this is to use system-on-chip (SoC) solutions that incorporate embedded DRAM, allowing wide on chip buses to connect logic to DRAM on the same die, rather than to external memory.
Furthermore, integration of DRAM directly into an LSI device has the added benefits of minimising system power consumption, saving board space, reducing component count and, thanks to the elimination of external buses, reducing the effects of EMI.
eDRAM is used in areas that require high memory bandwidth like in graphics accelerators and media-oriented vector processors like the Vector IRAM (VIRAM)..

Terahertz Waves And Applications

2011-01-08T10:42:00.000+05:30

Imaging technology has a rich history that began thousands of years ago. The reflection from a pool of still water or a shiny metal surface was arguably the first imaging method routinely used by mankind. With the advent of lenses, many other novel forms of optical imaging emerged, including telescopes and microscopes.
Using a lens, a pinhole camera, and a sensitized pewter plate, Niépce was the first person to permanently record an image. Optical photography and other forms of optical imaging have since become commonplace.
Of course, imaging has not been constrained to optical frequencies. In 1895 Roentgen discovered X-rays. As with X-rays, whenever a portion of the electromagnetic (EM) spectrum became practically usable, it wasn’t long before it was adapted to an imaging configuration.
Therefore, it is not surprising that many types of imaging systems exist today and utilize the radio, microwave, infrared (IR), visible, ultraviolet, X-ray, and gamma ray portions of the EM spectrum.
Pressure waves have also been adapted to imaging and are manifest in the various forms of ultrasonic and sonographic imaging systems.
Terahertz (THz) radiation (0.1 THz to 10 THz, 1 THz = 1012 Hz) lies between the infrared (night vision cameras) and microwave (operating range of mobile phones) region of the electromagnetic spectrum.
What makes these waves so fascinating to scientists is their ability to penetrate materials that are usually opaque to both visible and infrared radiation. For example, terahertz waves can pass through fog, fabrics, plastic, wood, ceramics and even a few centimeters of brick - although a metal object or a thin layer of water can block them.
The way in which terahertz waves interact with living matter has potential for highlighting the early signs of tooth decay and skin or breast cancer, or understanding cell dynamics.

VT Architecture

2011-01-08T10:39:00.000+05:30

Parallelism and locality are the key application characteristics exploited by computer architects to make productive use of increasing transistor counts while coping with wire delay and power dissipation. Conventional sequential ISAs provide minimal support for encoding parallelism or locality, so high-performance implementations are forced to devote considerable area and power to on-chip structures that extract parallelism or that support arbitrary global communication. The large area and power overheads are justified by the demand for even small improvements in performance on legacy codes for popular ISAs. Many important applications have abundant parallelism, however, with dependencies and communication patterns that can be statically determined. ISAs that expose more parallelism reduce the need for area and power intensive structures to extract dependencies dynamically. Similarly, ISAs that allow locality to be expressed reduce the need for long range communication and complex Interconnect.

                                                 The challenge is to develop an efficient encoding of an application’s parallel dependency graph and to reduce the area and power consumption of the micro architecture that will execute this dependency graph. All these challenges are met by unifying the vector and multithreaded execution models with the vector-thread (VT) architectural paradigm. VT allows large amounts of structured parallelism to be compactly encoded in a form that allows a simple micro architecture to attain high performance at low power by avoiding complex control and   datapath structures   and by reducing activity on long wires.
The VT programmer’s model extends a conventional scalar control processor with an array of slave virtual processors (VPs). VPs execute strings of RISC-like instructions packaged into  atomic instruction  blocks (AIBs). To execute data-parallel code, the control processor broadcasts AIBs to all the slave VPs. To execute thread parallel code, each VP directs its own control flow by fetching its own AIBs. Implementations of the VT architecture can also exploit instruction-level parallelism within AIBs. In this way, the VT architecture supports a
modeless intermingling of all forms of application parallelism. This flexibility provides new ways to parallelize codes that are difficult to vectorize or that incur   excessive synchronization costs when threaded. Instruction locality is improved by allowing common code to be factored out and executed only once on the control processor, and by executing the same AIB multiple times on each VP in turn.   Data locality is improved as most operand communication is isolated to within an individual VP.
SCALE, a prototype processor, is an instantiation of the vector-thread architecture designed for low-power and high-performance embedded systems. As transistors have become cheaper and faster, embedded applications have evolved from simple control functions to cellphones that run multitasking networked operating systems with real time video, three-dimensional graphics, and dynamic compilation of garbage collected languages. Many other embedded applications require sophisticated high-performance information processing, including streaming media devices, network routers, and wireless base stations. Benchmarks taken from these embedded domains can be mapped efficiently to the SCALE vectorthread architecture. In many cases, the codes exploit multiple types of parallelism simultaneously for greater efficiency

Zigbee - zapping away wired worries

2011-01-08T10:37:00.000+05:30

In recent years there has been rapid development in the wireless sector due to demand for wire free connectivity. Most of the development was focused on high data rate applications like file transfer etc with new standards like Bluetooth emerging.
During this time applications that required lower data rates but had some other special requirements were neglected in the sense that no open standard was available.
Either these applications we abandoned in the wireless arena or implemented using proprietary standards hurting the interoperability of the system.
ZigBee is a wireless standard that caters to this particular sector. Potential applications of ZigBee include Home Automation, Wireless Sensor Networks, Patient monitors etc. The key features of these applications and hence aims of ZigBee are

Low Cost
Low Power for increased battery life
Low Range
Low Complexity
Low Data Rates
Co-Existence with other long range Wireless Networks

The ZigBee standard is maintained by ZigBee Alliance is a spin off of the HomeRF group, an unsuccessful home automation related consortium.
It is built upon the IEEE 802.15.4 protocol which is intended for LR-WPAN (Low Rate - Wireless Personal Area Network).
In this seminar a general overview of ZigBee is followed by an analysis of how ZigBee and underlying 802.15.4 provide the aims mentioned. Also a brief comparisons with other solutions will be done.

Radiation Hardened Chips

2011-01-08T10:34:00.000+05:30

Space is a hostile environment. No atmosphere, extreme variations in temperature and almost no energy sources, where even the slightest of mistakes can lead to a disaster. The vast emptiness of space is filled with radiation, mostly from the sun.
A normal computer unless given proper shielding will not be able to work properly. Thus special types of chips- rad hard chips are used.

Radiation hardened chips are made by two methods: -

Radiation hardening by process (RHBP)
Radiation hardening by design (RHBD)

The latter method is much more cost effective and has a great potential for the future. . It has been demonstrated that RHBD techniques can provide immunity from total-dose and single-event effects in commercially produced circuits.
Commercially produced RHBD memories, microprocessors, and application-specific integrated circuits are now being used in defense&space industry.
Rad hard chips have a great scope in military application and protecting critical data (both industrial &domestic) from the vagaries of man and nature.

Current trends throughout military and space sectors favor the insertion of commercial off-the-shelf (COTS) technologies for satellite applications.
However, there are also unique concerns for assuring reliable performance in the presence of ionizing particle environments which present concerns in all orbits of interest. This seminar will detail these concerns from two important perspectives including premature device failure from total ionizing dose and also single particle effects which can cause both permanent failure and soft errors.

Terahertz Transistor

2011-01-08T10:32:00.000+05:30

MOS transistor is the building block of integrated circuits, and is the engine that powers them. 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 become a reality before 2010.
                    The semiconductor industry faces an environment that includes increasing chip complexity, continued cost pressures, increasing environmental regulations, and growing concern about energy consumption. New materials and technologies are needed to support the continuation of Moore's law.
                        Moore's Law was first postulated in 1965 and it has driven the research, development, and investments in the semiconductor industry for more than three decades. The observation that the number of transistors per integrated circuit doubles every eighteen to twenty four months is well known to industry analysts and many of the general public.
However, what is sometimes overlooked is that fact that Moore's law is an economic paradigm: that is, the cost of a transistor on an integrated circuit needs to be reduced by one half every two years.
This type of cost reduction cannot be sustained for an    extended   period by    straightforward    continuous     improvement    of existing technologies.
The semiconductor industry will face a number of challenges during this decade where new materials and new technologies will need to be introduced to support the continuation of Moore's Law.

FinFET Technology

2011-01-08T10:29:00.000+05:30

The introduction of FinFET Technology has opened new chapters in Nano-technology. Simulations show that FinFET structure should be scalable down to 10 nm. Formation of ultra thin fin enables suppressed short channel effects.

It is an attractive successor to the single gate MOSFET by virtue of its superior electrostatic properties and comparative ease of manufacturability.
Since the fabrication of MOSFET, the minimum channel length has been shrinking continuously. The motivation behind this decrease has been an increasing interest in high speed devices and in very large scale integrated circuits.
The sustained scaling of conventional bulk device requires innovations to circumvent the barriers of fundamental physics constraining the conventional MOSFET device structure. The limits most often cited are control of the density and location of dopants providing high I on /I off ratio and finite subthreshold slope and quantum-mechanical tunneling of carriers through thin gate from drain to source and from drain to body.
The channel depletion width must scale with the channel length to contain the off-state leakage I off. This leads to high doping concentration, which degrade the carrier mobility and causes junction edge leakage due to tunneling. Furthermore, the dopant profile control, in terms of depth and steepness, becomes much more difficult.
The gate oxide thickness tox must also scale with the channel length to maintain gate control, proper threshold voltage VT and performance. The thinning of the gate dielectric results in gate tunneling leakage, degrading the circuit performance, power and noise margin.

Magnetic Amplifiers

2011-01-08T10:27:00.002+05:30

A magnetic amplifier is a device which controls the power delivered from an a.c. source by employing a controllable non linear reactive elements or circuit generally interposed in series with the load. The power required to control the reactive element or circuit is made for less than the amount of power controlled; and hence power amplification is achieved. The non-linear reactive element is a saturable reactor. When used in a combination with a set of high-grade rectifiers, it exhibits power amplification properties in the sense that small changes in control power result in considerable changes in output power. The basic component of a magnetic amplifier, as mentioned above, is the saturable reactor. It consists of a laminated core of some magnetic material. The hysteresis loop of the reactor core is a narrow and steep one. A schematic diagram of a simple saturable core reactor with control winding and a.c. winding wound on two limbs. Thecontrol winding having a number of turns, Na.c. is fed with d.c. supply. By varying the control current, it is possible to largely vary the degree of saturation of the core. The other winding, called the a.c. winding or gate winding having a number of turns, Na.c. is fed from an a.c. source, the load being connected in series with it.
The property of the reactor which makes it behave as a power amplifier is its ability to change the degree of saturation of the core when the control winding mmf (magneto motive force i.e., ampere turns), established by d.c. excitation, is changed. The a.c. power supply will have high impedance if the core is unsaturated and the varying values of lower impedances as the core is increasingly saturated. When the core is completely saturated, the impedance of the a.c. winding becomes negligibly small and the full a.c. voltage appears across the load. Small values of current through the control winding, which has a large number of turns, will determine the degree of saturation of the core and hence change the impedance of the output circuit and control the flow of current through the load.
By making the ratio of control winding turns to the a.c. winding turns large, an extremely high value of output current can be controlled by a very small amount of control current, The saturable core reactor circuit shown in Fig. has certain serious disadvantages. The core gets partially desaturated in the half-cycle in which the a.c. winding mmf opposes the control winding mmf. This difficulty is overcome by employing a rectifier in the output circuit as shown in Fig. Here the desaturating (damagnetising) effect by the half-cycle of the output current is blocked by the rectifier. On the other hand, the output and control winding mmfs aid each other to effect saturation in the half-cycle in which current passes through the load, thus making the reactor a self-saturating magnetic amplifier.
Another difficulty that is experienced is that a high voltage is induced in the control winding due to transformer action. In order that this voltage is unable to send current to the d.c. circuit a high inductance should be connected in series with the control winding. This, however, slows down the response of the control system and hence the overall system. The saturable core is generally made of a saturable ferromagnetic material. For magnetic amplifiers of lower ratings usual transformer type construction using silicon steel (3 to 3.5 per cent Si) is used. Use of high quality nickel-iron alloy materials, however , makes possible much higher performance amplifiers of smaller size and weight. In order to realize the advantages of these materials, use is made of toroidal core configuration.

Illumination With Solid State Lighting

2011-01-08T10:27:00.001+05:30

A Light emitting diodes (LEDs) have gained broad recognition as the ubiquitous little lights that tell us that our monitors are on, the phone is off the hook or the oven is hot semiconductor.
The basic principle behind the emission of light is that: When charge carrier pairs recombine in a semiconductor with an appropriate energy band-gap generates light. In a forward biased diode, little recombination occurs in the depletion layer. Most occurs in a few microns of either P- region or N –region, depending on which one is lightly doped.
LEDs produce narrow band radiations, with wave length determined by energy band of the semiconductor. Solid state electronics have replaced their vacuum tube predecessors for almost five decades. However in the next decade they will be brighter, more efficient and inexpensive enough to replace conventional lighting sources (i.e. incandescent bulbs, fluorescent tubes).
Recent development in AlGaP and AlInGaP blue and green semiconductor growth technology have enabled applications where several single to several millions of these indicator LEDs can be packed together to be used in full color signs, automotive tail lambs, traffic lights etc. still the preponderance of applications require that the viewer has to look directly into the LED. This is not “SOLID STATE LIGHTING”
              Artificial lighting sources share three common characteristics:
       -They are rarely viewed directly: light from sources are viewed as reflection off the illuminated object.
      - The unit of measure is kilo lumen or higher not mille lumen or lumen as it is incase of LEDs
      -Lighting sources are pre dominantly white with CIE color coordinates, producing excellent color rendering
         Today there is no such commercially using “SOLID STATE LAMP” However high power LED sources are being developed, which will evolve into lighting
sources

Electrical Impedance Tomography Or EIT

2011-01-08T10:27:00.000+05:30

To begin with, the word tomography can be explained with reference to ‘tomo’ and
‘graphy’; ‘tomo’ originates from the Greek word ‘tomos’ which means section or slice,
and ‘graphy’ refers to representation. Hence tomography refers to any method which
involves reconstruction of the internal structural information within an object mathematically from a series of projections.
The projection here is the visual information probed using an emanation which are physical processes involved. These include physical processes such as radiation, wave motion, static field, electric current etc. which are used to study an object from outside.Medical tomography primarily uses X-ray absorption, magnetic resonance, positron emission, and sound waves (ultrasound) as the emanation.
Nonmedical area of application and research use ultrasound and many different frequencies of electromagnetic spectrum such as microwaves, gamma rays etc. for probing the visual information.
Besides photons, tomography is regularly performed using electrons and neutrons. In addition to absorption of the particles or radiation, tomography can be based on the scattering or emission of radiation or even using electric current as well.When electric current is consecutively fed through different available electrode pairs and the corresponding voltage, measured consecutively by all remaining electrode pairs, it is possible to create an image of the impedance of different regions of the volume conductor by using certain reconstruction algorithms. This imaging method is called impedance imaging.
admittance (admittivity) or specific impedance (impedivity) of tissue rather than the conductivity; hence, electric impedance tomography. Thus, EIT is an imaging method which maybe used to complement X-ray tomography (computer tomography, CT), ultrasound imaging, positron emission tomography (PET), and others.Because the image is usually constructed in two dimensions from a slice of the volume conductor, the method is also called impedance tomography and ECCT (electric current computed tomography), or simply, electrical impedance tomography or EIT.Electrical Impedance Tomography (EIT) is an imaging technology that applies time-varying currents to the surface of a body and records the resulting voltages in order to reconstruct and display the electrical conductivity and permittivity in the interior of the body. This technique exploits the electrical properties of tissues such as resistance and capacitance. It aims at exploiting the differences in the passive electrical properties of tissues in order to generate a tomographic image.Human tissue is not simply conductive. There is evidence that many tissues also demonstrate a capacitive component of current flow, and therefore, it is appropriate to speak of the specific impedance (impedivity) of tissue rather than the conductivity; hence, electric impedance tomography. Thus, EIT is an imaging method which maybe used to complement X-ray tomography (computer tomography, CT), ultrasound imaging, positron emission tomography (PET), and others.

Immersion Lithography

2011-01-08T10:25:00.002+05:30

The growth of the semiconductor industry is driven by Moore’s law: “The complexity for minimum component cost has increased at a rate of roughly a factor of two per year”. Notice that Moore observed that not only was the number of components doubling yearly, but was doing so at minimum cost.
One of the main factors driving the improvements in complexity and cost of ICs is improvements in optical lithography and the resulting ability to print ever smaller features.
Recently optical lithography, the backbone of the industry for 45 years has been pushing up against a number of physical barriers that have led to massive investments in development of alternate techniques such as Scalpel, Extreme Ultraviolet and others.
Since the mid eighties, the demise of optical lithography has been predicted as being only a few years away, but each time optical lithography approaches a limit, some new technique pushes out the useful life of the technology.
The recent interest in immersion lithography offers the potential for optical lithography to be given a reprieve to beyond the end of the decade.

Low Power Wireless Sensor Network

2011-01-08T10:24:00.000+05:30

Wireless distributed microsensor systems will enable fault tolerant monitoring and control of a variety of applications. Due to the large number of microsensor nodes that may be deployed and the long required system lifetimes, replacing the battery is not an option.
Sensor systems must utilize the minimal
possible energy while operating over a wide range of operating scenarios. This paper presents an overview of the key technologies required for low-energy distributed microsensors.
These include

power aware computation/communication component technology
low-energy signaling and networking
system partitioning considering computation
communication trade-offs
a power aware software infrastructure.

Tri-Gate Transistor

2011-01-08T10:21:00.000+05:30

Transistors are the microscopic, silicon-based switches that process the ones and zeros of the digital worlds and are the fundamental building block of all semiconductor chips. With traditional planar transistors, electronic signals travel as if on a flat, one-way road. This approach has served the semiconductor industry well since the 1960s. But, as transistors shrink to less than 30 nanometers (billionths of a meter), the increase in current leakage means that transistors require increasingly more power to function correctly, which generates unacceptable levels of heat.

Intel's tri-gate transistor employs a novel 3-D structure, like a raised, flat plateau with vertical sides, which allows electronic signals to be sent along the top of the transistor and along both vertical sidewalls as well. This effectively triples the area available for electrical signals to travel, like turning a one-lane road into a three-lane highway, but without taking up more space. Besides operating more efficiently at nanometer-sized geometries, the tri-gate transistor runs faster, delivering 20 percent more drive current than a planar design of comparable gate size.

The tri-gate structure is a promising approach for extending the TeraHertz transistor architecture Intel announced in December 2001. The tri-gate is built on an ultra-thin layer of fully depleted silicon for reduced current leakage. This allows the transistor to turn on and off faster, while dramatically reducing power consumption. It also incorporates a raised source and drain structure for low resistance, which allows the transistor to be driven with less power. The design is also compatible with the future introduction of a high K gate dielectric for even lower leakage.
Intel researchers have developed "tri-gate" transistor design. This is one of the major breakthroughs in the VLSI technology. The transistor is aimed at bringing down the transistor size in accordance with the Moore’s Law. The various problems transistors with very small size face have to be overcome. A reduction in power dissipation is another aim. This is to develop low power micro processors and flash memories.

Tri-gate transistors show excellent DIBL, high sub threshold slope, high drive and much better short channel performance compared to CMOS bulk transistor. The drive current is almost increased by 30%. The thickness requirement of the Si layer is also relaxed by about 2-3 times that of a CMOS bulk transistor.
Tri- gate transistors are expected to replace the nanometer transistors in the Intel microprocessors by 2010. 60 nm tri-gate transistors are already fabricated and 40 nm tri-gate transistors are under fabrication. Tri-gate transistor is going to play an important role in decreasing the power requirements of the future processors. It will also help to increase the battery life of the mobile devices.

DSP Enhanced FPGA

2011-01-08T10:20:00.000+05:30

Rapid advances in silicon technology and high demand of multimedia applications on wireless networks have spurred the research anddevelopment of computationally intensive signal processing and communication systems on FPGAs and Application Specific Integrated Circuits (ASICs).
These advancements also offer mystical solutions to historically intractable signal processing problems resulting in major new market opportunities and trends. Traditionally for signal processing specific applications off the shelf Digital Signal Processors (DSPs) are used.
Exploiting parallelism in algorithms and mapping them on VLIW processors are tedious and do not always give optimal solution. There are applications where even multiple of these DSPs cannot handle the computational needs of the applications.
Recent advances in speed, density, features and low cost have made FPGA processors offer a very attractive choice for mapping high-rate signal processing and communication systems, specially when the processing requirements are beyond the capabilities of off the shelf DSPs.
In many designs a combination of DSP and FPGA are used. The more structured and arithmetic demanding parts of the application are mapped on the FPGA and less structured parts of the algorithms are mapped on off the shelf DSPs.

Surface Mount Technology

2011-01-08T10:12:00.000+05:30

Surface mount technology is an easiest and prefect form of mounting components in Printed Circuit Boards. It entails making reliable interconnections on the board at great speeds, at reduced cost. To achieve these, SMT needed new types of surface mount components, new testing techniques, new assembling technique, new mounting techniques and a new set of design guidelines.
SMT is completely different from insertion mounting. The difference depends on the availability and cost of surface mounting elements. Thus the designer has no choice other than mixing the through hole and surface mount elements. At every step the surface mount technology calls for automation with intelligence.
Electronic products are becoming miniature with improvements in integration and interconnection on the chip itself, and device – to – device (D–to–D) interconnections. Surface Mount Technology (SMT) is a significant contributor to D–to–D interconnection costs.
In SMT, the following are important

D-to-D interconnection costs.
Signal integrity and operating speeds.
Device- to-substrate interconnection methods.
Thermal management of the assembled package.

D-to-D interconnection costs have not decreased as much as that of the ICs. A computer-on-a-chip costs less than the surrounding component interconnections. The problem of propagation delay, which is effectively solved at the device level, resurfaces as interconnections between the devices are made.
The modified new IC packages, having greater integration of functions, less in size and weight, and smaller in lead pitch, dictate newer methods of design, handling, assembly and repair. This has given new directions to design and process approaches, which are addresses by SMT.Currently, D-to-D interconnections at the board level are based on ‘soldering’-the method of joining the discrete components.
The leads of the components are inserted in the holes drilled as per the footprint, and soldered.In the early decades, manual skills were used to accomplish insertion as well as soldering, as the component sizes were big enough to be handled conveniently. There have been tremendous efforts to automate the method of insertion of component leads to their corresponding holes, and solder them en-mass. The leads always posed problems for auto-insertion. The tendency of Americans against using manual, skilled labour resulted in the emergence of SMT, which inherits with it automation as precondition for success.

Adaptive active phased array radars

2011-01-08T09:48:00.000+05:30

Adaptive active phased array radars are seen as the vehicle to address the current requirements for true ‘multifunction’ radars systems. Their ability to adapt to the enviournment and schedule their tasks in real time allows them to operate with performance levels well above those that can be achieved from the conventional radars.
Their ability to make effective use of all the available RF power and to minimize RF losses also makes them a good candidate for future very long range radars. The AAPAR can provide many benefit in meeting the performance that will be required by tommorow's radar systems. In some cases it will be the only possible solution.
It provides the radar system designer with an almost infinte range of possibilites. This flexibility, however, needs to be treated with caution: the complexity of the system must not be allowed to grow such that it becomes uncontolled and unstable. The AAPAR breaks down the conventional walls between the traditional systems elements- antenna, transmitter, receiver etc-such that the AAPAR design must be treated holistically.
Strict requirements on the integrity of the system must be enforced. Rigourous techiues must be used to ensure that the overall flow down of requirements from top level is achieved and that testeability of the requirements can be demonstrated under both quiescent and adaptive condition.

Type 2 Superconductors

2010-12-02T19:34:00.002+05:30

  Except for the elements vanadium, technetium and niobium, the Type 2 category of superconductors is comprised of metallic compounds and alloys. The recently-discovered superconducting "perovskites" (metal-oxide ceramics that normally have a ratio of 2 metal atoms to every 3 oxygen atoms) belong to this Type 2 group. They achieve higher Tc's than Type 1 superconductors by a mechanism that is still not completely understood. Conventional wisdom holds that it relates to the planar layering within the crystalline structure (see above graphic). Although, other recent researchsuggests the holes of hypocharged oxygen in the charge reservoirs are responsible. (Holes are positively-charged vacancies within the lattice.) The superconducting cuprates (copper-oxides) have achieved astonishingly high Tc's when you consider that by 1985 known Tc's had only reached 23 Kelvin. To date, the highest Tc attained at ambient pressure for a material that will form stoichiometrically (by formula) has been 138 K. And the highest Tc overall is 265K for a material which does not form stoichiometrically (see below list). One theory predicts an upper limit for the layered cuprates (Vladimir Kresin, Phys. Reports 288, 347 - 1997). Others assert there is no limit. Either way, it is almost certain that other, more-synergistic compounds still await discovery among the high-temperature superconductors.
     The first superconducting Type 2 compound, an alloy of lead and bismuth, was fabricated in 1930 by W. de Haas and J. Voogd. But, was not recognized as such until later, after the Meissner effect had been discovered. This new category of superconductors was identified by L.V. Shubnikov at the Kharkov Institute of Science and Technology in the Ukraine in 1936⁽¹⁾ when he found two distinct critical magnetic fields (known as H_c1 and H_c2) in PbTl₂. The first of the oxide superconductors was created in 1973 by DuPont researcher Art Sleight when Ba(Pb,Bi)O₃ was found to have a Tc of 13K. The superconducting oxocuprates followed in 1986.
     Type 2 superconductors - also known as the "hard" superconductors - differ from Type 1 in that their transition from a normal to a superconducting state is gradual across a region of "mixed state" behavior. Since a Type 2 will allow some penetration by an external magnetic field into its surface, this creates some rather novel mesoscopic phenomena like superconducting "stripes" and "flux-lattice vortices". While there are far too many to list in totality, some of the more interesting Type 2 superconductors are listed below by similarity and with descending Tc's. Where available, the lattice structure of the system is also noted.

(Tl₄Ba)Ba₂MgCu₈O₁₃₊
     (As a 9223 structure)

(Tl₄Ba)Ba₂Mg₂Cu₇O₁₃₊
     (As a 9223 structure)

(Tl₄Ba)Ba₂Ca₂Cu₇O₁₃₊
     (As a 9223 structure)

(Tl₄Ba)Ba₄Ca₂Cu₁₀O_y
     (As a 9212/2212C intergrowth.)

Tl₅Ba₄Ca₂Cu₁₀O_y
     (As a 9212/2212C intergrowth.)

(Sn₅In)Ba₄Ca₂Cu₁₁O_y
     (As a B212/2212C intergrowth.)

(Sn₅In)Ba₄Ca₂Cu₁₀O_y
     (As a B212/1212C intergrowth.)

Sn₆Ba₄Ca₂Cu₁₀O_y
     (As a B212/1212C intergrowth.)

(Sn_1.0Pb_0.5In_0.5)Ba₄Tm₆Cu₈O₂₂₊
     (As a 1256/1212 intergrowth.)

(Sn_1.0Pb_0.5In_0.5)Ba₄Tm₅Cu₇O₂₀₊
     (As a 1245/1212 intergrowth.)

(Sn_1.0Pb_0.5In_0.5)Ba₄Tm₄Cu₆O₁₈₊
     (As a 1234/1212 intergrowth)

Sn₃Ba₄Ca₂Cu₇O_y
     (As a 5212/1212C intergrowth.)

~265 K

~258 K

~254 K

~242 K

~233 K

~218 K

~212 K

~200 K

~195 K

~185 K

~163 K

~160 K

(Hg_0.8Tl_0.2)Ba₂Ca₂Cu₃O_8.33
HgBa₂Ca₂Cu₃O₈
HgBa₂Ca₃Cu₄O₁₀₊
HgBa₂(Ca_1-xSr_x)Cu₂O₆₊
HgBa₂CuO₄+

138 K^*
133-135 K
125-126 K
123-125 K
94-98 K

Lattice: TET

* Note: As a result of a topological "defect", Hg will also go into the Cu atomic sites. Thus, the volume fraction of the intended structure type is considerably less than 100%.

Tl₂Ba₂Ca₂Cu₃O₁₀
(Tl_1.6Hg_0.4)Ba₂Ca₂Cu₃O₁₀₊
TlBa₂Ca₂Cu₃O₉₊
(TlSn)Ba₄TmCaCu₄O_x
(Tl_0.5Pb_0.5)Sr₂Ca₂Cu₃O₉
Tl₂Ba₂CaCu₂O₆
TlBa₂Ca₃Cu₄O₁₁
TlBa₂CaCu₂O₇₊
Tl₂Ba₂CuO₆
TlSnBa₄Y₂Cu₄O_x
127-128 K
  126 K
  123 K
~121 K  (Superconductors.ORG - 2005)
118-120 K
   118 K
   112 K
   103 K
    95 K
    86 K   (Superconductors.ORG - 2007)

Lattice: TET

Sn₄Ba₄(Tm₂Ca)Cu₇O_x
Sn₂Ba₂(Tm_0.5Ca_0.5)Cu₃O₈₊
SnInBa₄Tm₃Cu₅O_x
Sn₃Ba₄Tm₃Cu₆O_x
Sn₃Ba₈Ca₄Cu₁₁O_x
SnBa₄Y₂Cu₅O_x
Sn₄Ba₄Tm₂YCu₇O_x
Sn₄Ba₄TmCaCu₄O_x
Sn₄Ba₄Tm₃Cu₇O_x
Sn₂Ba₂(Y_0.5Tm_0.5)Cu₃O₈₊
Sn₃Ba₄Y₂Cu₅O_x
SnInBa₄Tm₄Cu₆O_x
Sn₂Ba₂(Sr_0.5Y_0.5)Cu₃O₈
Sn₄Ba₄Y₃Cu₇O_x ~127 K    (TmTm-Ca structure only)
~115 K  (Superconductors.ORG - 2005)
~113 K  (Superconductors.ORG - 2005)
  109 K  (Superconductors.ORG - 2007)
  109 K  (One-of-a-Kind Resonant - 2006)
  107 K    (Superconductors.ORG - 2007)
~104 K  (First Hi-Tc Reentrant - 2007)
~100 K   (Superconductors.ORG - 2007)
~98 K  (Superconductors.ORG - 2006)
~96 K  (Superconductors.ORG - 2007)
~91 K  (Superconductors.ORG - 2006)
   87 K    (Superconductors.ORG - 2005)
   86 K     (Aleksandrov, et al - 1989)
~80 K   (Superconductors.ORG - 2005)

Bi_1.6Pb_0.6Sr₂Ca₂Sb_0.1Cu₃O_y
Bi₂Sr₂Ca₂Cu₃O₁₀^***
Bi₂Sr₂CaCu₂O₉^***
Bi₂Sr₂(Ca_0.8Y_0.2)Cu₂O₈
Bi₂Sr₂CaCu₂O₈ 115 K (thick film on MgO substrate)
110 K
110 K
95-96K
91-92K

Lattice: ORTH*** Though not always listed as a component, a small amount of Lead (x=.2-.26) is often used with Bismuth compounds to help facilitate a higher-Tc crystalline phase.

(Ca_1-xSr_x)CuO₂
YSrCa₂Cu₄O₈₊
(Ba,Sr)CuO₂
BaSr₂CaCu₄O₈₊
(La,Sr)CuO₂ 110 K
101 K    (Superconductors.ORG - 2007)
90 K
90 K     (Superconductors.ORG - 2007)
42 K

*** The above 5 compounds are all "infinite layer".

Pb₃Sr₄Ca₃Cu₆O_x
Pb₃Sr₄Ca₂Cu₅O₁₅₊
(Pb_1.5Sn_1.5)Sr₄Ca₂Cu₅O₁₅₊
Pb₂Sr₂(Ca, Y)Cu₃O₈ 106 K    (Superconductors.ORG - 2007)
101 K    (Superconductors.ORG - 2005)
~95 K    (Superconductors.ORG - 2006)
70 K   (Cava, et al - 1989)

AuBa₂Ca₃Cu₄O₁₁
AuBa₂(Y, Ca)Cu₂O₇
AuBa₂Ca₂Cu₃O₉ 99 K    (Kopnin, et al - 2001)
82 K
  30 K

Lattice: ORTH

YBa₃Cu₄O_x   (9223C structure)
YCaBa₃Cu₅O₁₁₊
(Y_0.5Lu_0.5)Ba₂Cu₃O₇
(Y_0.5Tm_0.5)Ba₂Cu₃O₇
Y₃Ba₅Cu₈O_x
Y₃CaBa₄Cu₈O₁₈₊
(Y_0.5Gd_0.5)Ba₂Cu₃O₇
Y₂CaBa₄Cu₇O₁₆
Y₃Ba₄Cu₇O₁₆
Y₂Ba₅Cu₇O_x
NdBa₂Cu₃O₇
Y₂Ba₄Cu₇O₁₅
GdBa₂Cu₃O₇
YBa₂Cu₃O₇
TmBa₂Cu₃O₇
YbBa₂Cu₃O₇
YSr₂Cu₃O₇

Lattice: TET
177 K   (Superconductors.ORG - 2009)
107 K    (Superconductors.ORG - 2010)
107 K    (Superconductors.ORG - 2005)
105 K (Superconductors.ORG - 2005)
105 K (Superconductors.ORG - 2008)
99 K    (Superconductors.ORG - 2010)
97 K    (Superconductors.ORG - 2005)
96 K   (Superconductors.ORG - 2006)
96 K    (Superconductors.ORG - 2005)
96 K    (Superconductors.ORG - 2008)
96 K
95 K
94 K
92 K   (See above graphic)
90 K
89 K
62 K

Comment: "1-2-3" superconductors actually have the 1212C structure. Thus, the formula for YBCO could be written CuBa₂YCu₂O₇.

GaSr₂(Ca_0.5Tm_0.5)Cu₂O₇
Ga₂Sr₄Y₂CaCu₅O_x
Ga₂Sr₄Tm₂CaCu₅O_x
La₂Ba₂CaCu₅O₉₊
(Sr,Ca)₅Cu₄O₁₀
GaSr₂(Ca, Y)Cu₂O₇
(In_0.3Pb_0.7)Sr₂(Ca_0.8Y_0.2)Cu₂O_x
(La,Sr,Ca)₃Cu₂O₆
La₂CaCu₂O₆₊
(Eu,Ce)₂(Ba,Eu)₂Cu₃O₁₀₊
(La_1.85Sr_0.15)CuO₄
SrNdCuO^****
(La,Ba)₂CuO₄
(Nd,Sr,Ce)₂CuO₄
Pb₂(Sr,La)₂Cu₂O₆
(La_1.85Ba_.15)CuO₄
99 K    (Superconductors.ORG - 2006)
85 K    (Superconductors.ORG - 2006)
81 K    (Superconductors.ORG - 2006)
79 K  (Saurashtra Univ., Rajkot, India - 2002)
70 K
70 K
60 K
58 K
45 K
43 K
40 K
40 K
35-38 K
35 K
32 K
30 K   (First HTS ceramic SC discovered - 1986)

**** First ceramic superconductor discovered without a non-superconducting oxide layer.
Comment: All of the above are copper perovskites, even though their metal-to-oxygen ratios are not exactly 2-to-3. The best performers are those compounds that contain one or more of the electron-emitters BaO, SrO or CaO, along with a Period 6 heavy metal like Mercury, Thallium, Lead, Bismuth, or Gold.

GdFeAsO1-x
(Ca,Sr,Ba)Fe₂As₂ LiFeAs
  53.5 K  (Highest Tc iron-based compound)
38 K
18 K

Comment: The above are members of the newly discovered iron pnictide family.

MgB₂
Ba_0.6K_0.4BiO₃
39 K  (Highest Tc Non-Fullerene Alloy)
30 K   (First 4th order phase compound)

Nb₃Ge
Nb₃Si
Nb₃Sn
Nb₃Al
V₃Si
Ta₃Pb
V₃Ga
Nb₃Ga
V₃In 23.2 K
19 K
18.1 K
18 K
17.1 K
17 K
16.8 K
14.5 K
13.9 K

  Lattice: A15  Comment: Among the binary alloys, these are some of the best performers; combining Group 5B metals in a ratio of 3-to-1 with 4A or 3A elements.

PuCoGa₅ 18.5 K    (First SC transuranic compound)

NbN 16.1 K

Comment: After NbTi (below) NbN is the most widely used low-temperature superconductor.

Nb_0.6Ti_0.4
MgCNi₃ 9.8 K      (First superconductive wire)
7-8 K      (First all-metal perovskite superconductor)

C
Nb
Tc
V 15 K      (as highly-aligned, single-walled nanotubes)
9.25 K
7.80 K
5.40 K

Lattice: C=Fullerene, Nb=BCC, Tc=HEX, V=BCC

Comment: These four are the only elemental Type 2 superconductors.

RuSr₂(Gd,Eu,Sm)Cu₂O₈
ErNi₂B₂C
YbPd₂Sn
UGe₂
URhGe₂
AuIn₃ Tc ~58 K  (Ruthenium-oxocuprate)
Tc 10.5 K    (Nickel-Borocarbide)
Tc ~2.5 K  (Heusler compound)
Tc ~1K    (Heavy fermion)
Tc ~1K             ( " )
Tc 50 uK

Comment: The above 6 compounds are all rare ferromagnetic superconductors.

Sr_.08WO₃
Tl_.30WO₃
Rb_.27-.29WO₃ 2-4 K    (Tungsten-bronze)
2.0-2.14 K         (")
  1.98 K              (")

Lattice: TET

SrTiO₃   0.35 K

Comment: This is the first oxide insulator found to be superconductive

Type 1 Superconductors And a Periodic Chart Comparison

2010-12-02T19:25:00.000+05:30

The Type 1 category of superconductors is mainly comprised of metals and metalloids that show some conductivity at room temperature. They require incredible cold to slow down molecular vibrations sufficiently to facilitate unimpeded electron flow in accordance with what is known as BCS theory. BCS theory suggests that electrons team up in "Cooper pairs" in order to help each other overcome molecular obstacles - much like race cars on a track drafting each other in order to go faster. Scientists call this process phonon-mediated coupling because of the sound packets generated by the flexing of the crystal lattice.
Type 1 superconductors - characterized as the "soft" superconductors - were discovered first and require the coldest temperatures to become superconductive. They exhibit a very sharp transition to a superconducting state (see above graph) and "perfect" diamagnetism - the ability to repel a magnetic field completely. Below is a list of known Type 1 superconductors along with the critical transition temperature (known as Tc) below which each superconducts. The 3rd column gives the lattice structure of the solid that produced the noted Tc. Surprisingly, copper, silver and gold, three of the best metallic conductors, do not rank among the superconductive elements. Why is this ?

Lead (Pb)
Lanthanum (La)
Tantalum (Ta)
Mercury (Hg)
Tin (Sn)
Indium (In)
Palladium (Pd)*
Chromium (Cr)*
Thallium (Tl)
Rhenium (Re)
Protactinium (Pa)
Thorium (Th)
Aluminum (Al)
Gallium (Ga)
Molybdenum (Mo)
Zinc (Zn)
Osmium (Os)
Zirconium (Zr)
Americium (Am)
Cadmium (Cd)
Ruthenium (Ru)
Titanium (Ti)
Uranium (U)
Hafnium (Hf)
Iridium (Ir)
Beryllium (Be)
Tungsten (W)
Platinum (Pt)*
Lithium (Li)
Rhodium (Rh)

7.196 K
4.88 K
4.47 K
4.15 K
3.72 K
3.41 K
3.3 K
3 K
2.38 K
1.697 K
1.40 K
1.38 K
1.175 K
1.083 K
0.915 K
0.85 K
0.66 K
0.61 K
0.60 K
0.517 K
0.49 K
0.40 K
0.20 K
0.128 K
0.1125 K
0.023 K (SRM 768)
0.0154 K
0.0019 K
0.0004 K
0.000325 K

FCC
HEX
BCC
RHL
TET
TET
(see note 1)
(see note 1)
HEX
HEX
TET
FCC
FCC
ORC
BCC
HEX
HEX
HEX
HEX
HEX
HEX
HEX
ORC
HEX
FCC
HEX
BCC

Uses for Superconductors

2010-12-02T16:20:00.000+05:30

Magnetic-levitation is an application where superconductors perform extremely well. Transport vehicles such as trains can be made to "float" on strong superconducting magnets, virtually eliminating friction between the train and its tracks. Not only would conventional electromagnets waste much of the electrical energy as heat, they would have to be physically much larger than superconducting magnets. A landmark for the commercial use of MAGLEV technology occurred in 1990 when it gained the status of a nationally-funded project in Japan. The Minister of Transport authorized construction of theYamanashi Maglev Test Line which opened on April 3, 1997. In December 2003, the MLX01 test vehicle (shown above) attained an incredible speed of 361 mph (581 kph).

   Although the technology has now been proven, the wider use of MAGLEV vehicles has been constrained by political and environmental concerns (strong magnetic fields can create a bio-hazard). The world's first MAGLEV train to be adopted into commercial service, a shuttle in Birmingham, England, shut down in 1997 after operating for 11 years. A Sino-German maglev is currently operating over a 30-km course at Pudong International Airport in Shanghai, China. The U.S. plans to put its first (non-superconducting) Maglev train into operation on a Virginia college campus. Click this link for a website that listsother uses for MAGLEV.

MRI of a human skull.     An area where superconductors can perform a life-saving function is in the field of biomagnetism. Doctors need a non-invasive means of determining what's going on inside the human body. By impinging a strong superconductor-derived magnetic field into the body, hydrogen atoms that exist in the body's water and fat molecules are forced to accept energy from the magnetic field. They then release this energy at a frequency that can be detected and displayed graphically by a computer. Magnetic Resonance Imaging (MRI) was actually discovered in the mid 1940's. But, the first MRI exam on a human being was not performed until July 3, 1977. And, it took almost five hours to produce one image! Today's faster computers process the data in much less time. A tutorial is available on MRI at this link. Or read the latest MRI news at this link.
     The Korean Superconductivity Group within KRISS has carried biomagnetic technology a step further with the development of a double-relaxation oscillation SQUID (Superconducting QUantum Interference Device) for use in Magnetoencephalography. SQUID's are capable of sensing a change in a magnetic field over a billion times weaker than the force that moves the needle on a compass (compass: 5e-5T, SQUID: e-14T.). With this technology, the body can be probed to certain depths without the need for the strong magnetic fields associated with MRI's.

      Probably the one event, more than any other, that has been responsible for putting "superconductors" into the American lexicon was the Superconducting Super-Collider project planned for construction in Ellis county, Texas. Though Congress cancelled the multi-billion dollar effort in 1993, the concept of such a large, high-energy collider would never have been viable without superconductors. High-energy particle research hinges on being able to accelerate sub-atomic particles to nearly the speed of light. Superconductor magnets make this possible. CERN, a consortium of several European nations, is doing something similar with its Large Hadron Collider (LHC) recently inaugurated along the Franco-Swiss border.

     Other related web sites worth visiting include the proton-antiproton collider page at Fermilab. This was the first facility to use superconducting magnets. Get information on the electron-proton collider HERA at the German lab pages of DESY (with English text). And Brookhaven National Laboratory features a page dedicated to its RHIC heavy-ion collider.

     Electric generators made with superconducting wire are far more efficient than conventional generators wound with copper wire. In fact, their efficiency is above 99% and their size about half that of conventional generators. These facts make them very lucrative ventures for power utilities. General Electrichas estimated the potential worldwide market for superconducting generators in the next decade at around $20-30 billion dollars. Late in 2002 GE Power Systems received $12.3 million in funding from the U.S. Department of Energy to move high-temperature superconducting generator technology toward full commercialization. To read the latest news on superconducting generators click Here.
     Other commercial power projects in the works that employ superconductor technology include energy storage to enhance power stability. American Superconductor Corp. received an order from Alliant Energy in late March 2000 to install a Distributed Superconducting Magnetic Energy Storage System (D-SMES) in Wisconsin. Just one of these 6 D-SMES units has a power reserve of over 3 million watts, which can be retrieved whenever there is a need to stabilize line voltage during a disturbance in the power grid. AMSC has also installed more than 22 of its D-VAR systems to provide instantaneous reactive power support.

The General Atomics/Intermagnetics General superconducting
Fault Current Controller, employing HTS superconductors.     Recently, power utilities have also begun to use superconductor-based transformers and "fault limiters". The Swiss-Swedish company ABB was the first to connect a superconducting transformer to a utility power network in March of 1997. ABB also recently announced the development of a 6.4MVA (mega-volt-ampere) fault current limiter - the most powerful in the world. This new generation of HTS superconducting fault limiters is being called upon due to their ability to respond in just thousandths of a second to limit tens of thousands of amperes of current. Advanced Ceramics Limited is another of several companies that makes BSCCO type fault limiters. Intermagnetics General recently completed tests on its largest (15kv class) power-utility-size fault limiter at a Southern California Edison (SCE) substation near Norwalk, California. And, both the US and Japan have plans to replace underground copper power cables with superconducting BSCCO cable-in-conduit cooled with liquid nitrogen. (See photo below.) By doing this, more current can be routed through existing cable tunnels. In one instance 250 pounds of superconducting wire replaced 18,000 pounds of vintage copper wire, making it over 7000% more space-efficient.
     An idealized application for superconductors is to employ them in the transmission of commercial power to cities. However, due to the high cost and impracticality of cooling miles of superconducting wire to cryogenic temperatures, this has only happened with short "test runs". In May of 2001 some 150,000 residents of Copenhagen, Denmark, began receiving their electricity through HTS (high-temperature superconducting) material. That cable was only 30 meters long, but proved adequate for testing purposes. In the summer of 2001 Pirelli completed installation of three 400-foot HTS cables for Detroit Edison at the Frisbie Substation capable of delivering 100 million watts of power. This marked the first time commercial power has been delivered to customers of a US power utility through superconducting wire. Intermagnetics General has announced that its IGC-SuperPower subsidiary has joined with BOC and Sumitomo Electric in a $26 million project to install an underground, HTS power cable in Albany, New York, in Niagara Mohawk Power Corporation's power grid. Sumitomo Electric's DI-BSCCO cable was employed in the first in-grid power cable demonstration project sponsored by the U.S. Department of Energy and New York Energy Research & Development Authority. After connecting to the grid successfully on July 2006, the DI-BSCCO cable has been supplying the power to approximately 70,000 households without any problems. The long-term test will be completed in the 2007-2008 timeframe.

Hypres Superconducting Microchip,
Incorporating 6000 Josephson Junctions.
      The National Science Foundation, along with NASA and DARPA and various universities, are currently researching "petaflop" computers. A petaflop is a thousand-trillion floating point operations per second. Today's fastest computers have reached "petaflop" speeds - quadrillions of operations per second. Currently the fastest is China’s Tianhe-1A, operating at 2.67 petaflops per second. The fastest single processor is a Lenslet optical DSP running at 8 teraflops. It has been conjectured that devices on the order of 50 nanometers in size along with unconventional switching mechanisms, such as the Josephson junctions associated with superconductors, will be necessary to achieve the next level of processing speeds. TRW researchers (now Northrop Grumman) have quantified this further by predicting that 100 billion Josephson junctions on 4000 microprocessors will be necessary to reach 32 petabits per second. These Josephson junctions are incorporated into field-effect transistors which then become part of the logic circuits within the processors. Recently it was demonstrated at the Weizmann Institute in Israel that the tiny magnetic fields that penetrate Type 2 superconductors can be used for storing and retrieving digital information. It is, however, not a foregone conclusion that computers of the future will be built around superconducting devices. Competing technologies, such as quantum (DELTT) transistors, high-density molecule-scale processors , and DNA-based processing also have the potential to achieve petaflop benchmarks.

     In the electronics industry, ultra-high-performance filters are now being built. Since superconducting wire has near zero resistance, even at high frequencies, many more filter stages can be employed to achive a desired frequency response. This translates into an ability to pass desired frequencies and block undesirable frequencies in high-congestion rf (radio frequency) applications such as cellular telephone systems. ISCO International andSuperconductor Technologies are companies currently offering such filters.

      Superconductors have also found widespread applications in the military. HTSC SQUIDS are being used by the U.S. NAVY to detect mines and submarines. And, significantly smaller motors are being built for NAVY ships using superconducting wire and "tape". In mid-July, 2001, American Superconductor unveiled a 5000-horsepower motor made with superconducting wire (below). An even larger 36.5MW HTS ship propulsion motor was delivered to the U.S. Navy in late 2006

      The newest application for HTS wire is in the degaussing of naval vessels. American Superconductor has announced the development of asuperconducting degaussing cable. Degaussing of a ship's hull eliminates residual magnetic fields which might otherwise give away a ship's presence. In addition to reduced power requirements, HTS degaussing cable offers reduced size and weight.

      The military is also looking at using superconductive tape as a means of reducing the length of very low frequency antennas employed on submarines. Normally, the lower the frequency, the longer an antenna must be. However, inserting a coil of wire ahead of the antenna will make it function as if it were much longer. Unfortunately, this loading coil also increases system losses by adding the resistance in the coil's wire. Using superconductive materials can significantly reduce losses in this coil. The Electronic Materials and Devices Research Group at University of Birmingham (UK) is credited with creating the first superconducting microwave antenna. Applications engineers suggest that superconducting carbon nanotubes might be an ideal nano-antenna for high-gigahertz and terahertz frequencies, once a method of achieving zero "on tube" contact resistance is perfected.

      The most ignominious military use of superconductors may come with the deployment of "E-bombs". These are devices that make use of strong, superconductor-derived magnetic fields to create a fast, high-intensity electro-magnetic pulse (EMP) to disable an enemy's electronic equipment. Such a device saw its first use in wartime in March 2003 when US Forces attacked an Iraqi broadcast facility.

A photo of Comet 73P/Schwassmann-Wachmann 3, in the act of disintegrating ,
taken with the European Space Agency S-CAM.      Among emerging technologies are a stabilizing momentum wheel (gyroscope) for earth-orbiting satellites that employs the "flux-pinning" properties of imperfect superconductors to reduce friction to near zero. Superconducting x-ray detectors and ultra-fast, superconducting light detectors are being developed due to their inherent ability to detect extremely weak amounts of energy. Already Scientists at the European Space Agency (ESA) have developed what's being called the S-Cam, an optical camera of phenomenal sensitivity (see above photo). And, superconductors may even play a role in Internet communications soon. In late February, 2000, Irvine Sensors Corporation received a $1 million contract to research and develop a superconducting digital router for high-speed data communications up to 160 Ghz. Since Internet traffic is increasing exponentially, superconductor technology may be called upon to meet this super need. Irvine Sensors speculates this router may see use in facilitating Internet2.

      According to June 2002 estimates by the Conectus consortium, the worldwide market for superconductor products is projected to grow to near US $38 billion by 2020. Low-temperature superconductors are expected to continue to play a dominant role in well-established fields such as MRI and scientific research, with high-temperature superconductors enabling newer applications. The above ISIS graph gives a rough breakdown of the various markets in which superconductors are expected to make a contribution.

      All of this is, of course, contingent upon a linear growth rate. Should new superconductors with higher transition temperatures be discovered, growth and development in this exciting field could explode virtually overnight.

     Another impetus to the wider use of superconductors is political in nature. The reduction of green-house gas (GHG) emissions has becoming a topical issue due to the Kyoto Protocol which requires the European Union (EU) to reduce its emissions by 8% from 1990 levels by 2012. Physicists in Finland have calculated that the EU could reduce carbon dioxide emissions by up to 53 million tons if high-temperature superconductors were used in power plants.
      The future melding of superconductors into our daily lives will also depend to a great degree on advancements in the field of cryogenic cooling. New, high-efficiency magnetocaloric-effect compounds such as gadolinium-silicon-germanium are expected to enter the marketplace soon. Such materials should make possible compact, refrigeration units to facilitate additional HTS applications. Stay tuned !

2010-12-02T16:13:00.000+05:30

   The first company to capitalize on high-temperature superconductors was Illinois Superconductor (today known as ISCO International), formed in 1989. This amalgam of government, private-industry and academic interests introduced a depth sensor for medical equipment that was able to operate at liquid nitrogen temperatures (~ 77K).
     In recent years, many discoveries regarding the novel nature of superconductivity have been made. In 1997 researchers found that at a temperature very near absolute zero an alloy of gold and indium was both a superconductor and a natural magnet. Conventional wisdom held that a material with such properties could not exist!  Since then, over a half-dozen such compounds have been found. Recent years have also seen the discovery of the first high-temperature superconductor that does NOT contain any copper (2000), and the first all-metal perovskite (2001).
     Also in 2001 a material that had been sitting on laboratory shelves for decades was found to be an extraordinary new superconductor. Japanese researchers measured the transition temperature of magnesium diboride at 39 Kelvin - far above the highest Tc of any of the elemental or binary alloy superconductors. While 39 K is still well below the Tc's of the "warm" ceramic superconductors, subsequent refinements in the way MgB₂ is fabricated have paved the way for its use in industrial applications. Laboratory testing has found MgB₂ will outperform NbTi and Nb₃Sn wires in high magnetic field applications like MRI.
     Though a theory to explain high-temperature superconductivity still eludes modern science, clues occasionally appear that contribute to our understanding of the exotic nature of this phenomenon. In 2005, for example, Superconductors.ORG discovered that increasing the weight ratios of alternating planes within the layered perovskites can often increase Tc significantly. This has led to the discovery of more than 40 new high-temperature superconductors, including a candidate for a new world record.
     The most recent "family" of superconductors to be discovered is the "pnictides". These iron-based superconductors were first observed by a group of Japanese researchers in 2006. Like the high-Tc copper-oxides, the exact mechanism that facilitates superconductivity in them is a mystery. However, with Tc's over 50K, a great deal of excitement has resulted from their discovery.
     Researchers do agree on one thing: discovery in the field of superconductivity is as much serendipity as it is science. Stay tuned!