Seminar 5z234c

Third Generation Solid State Drives Abstract The explosion of flash memory technology has dramatically increased storage capacity and decreased the cost of non-volatile semiconductor memory. The technology has fueled the proliferation of USB flash drives and is now poised to replace magnetic hard disks in some applications. A solid state drive (SSD) is a non-volatile memory system that emulates a magnetic hard disk drive (HDD). SSDs do not contain any moving parts, however, and depend on flash memory chips to store data. With proper design, an SSD is able to provide high data transfer rates, low access time, improved tolerance to shock and vibration, and reduced power consumption. For some applications, the improved performance and durability outweigh the higher cost of an SSD relative to an HDD. Using flash memory as a hard disk replacement is not without challenges. The nano-scale of the memory cell is pushing the limits of semiconductor physics. Extremely thin insulating glass layers are necessary for proper operation of the memory cells. These layers are subjected to stressful temperatures and voltages, and their insulating properties deteriorate over time. Quite simply, flash memory can wear out. Fortunately, the wear-out physics are well understood and data management strategies are used to compensate for the limited lifetime of flash memory. Flash memory was invented by Dr. Fujio Masuoka while working for Toshiba in 1984. The name "flash" was suggested because the process of erasing the memory contents reminded him of the flash of a camera. Flash memory chips store data in a large array of floating gate metal–oxide– semiconductor (MOS) transistors. Silicon wafers are manufactured with microscopic transistor dimension, now approaching 40 nanometers. Intel Corporation introduces its highly anticipated third-generation solid-state drive (SSD) the Intel Solid-State Drive 320 Series. Based on its industry-leading 25-nanometer (nm) NAND flash memory, the Intel SSD 320 replaces and builds on its high-performing Intel X25-M SATA SSD. Delivering more performance and uniquely architected reliability features, the new Intel SSD 320 offers new higher capacity models, while taking advantage of cost benefits from its 25nm process with an up to 30 percent price reduction over its current generation.

Floating Gate Flash Memory Cells SSDs mainly depend on flash memory chips to store data. The name "flash" was suggested because the process of erasing the memory contents reminded him of the flash of a camera. Flash memory chips store data in a large array of floating gate metal–oxide–semiconductor (MOS) transistors. Silicon wafers are manufactured with microscopic transistor dimension, now approaching 40 nanometers. In this flash memory thin insulating glass layers are necessary for proper operation of the memory cells. These layers are subjected to stressful temperatures and voltages, and their insulating properties deteriorate over time. Quite simply, flash memory can wear out. A floating gate memory cell is a type of metal-oxide-semiconductor field-effect transistor (MOSFET). Silicon forms the base layer, or substrate, of the transistor array. Areas of the silicon are masked off and infused with different types of impurities in a process called doping. Impurities are carefully added to adjust the electrical properties of the silicon.

Some impurities, for example phosphorous, create an excess of electrons in the silicon lattice. Other impurities, for example boron, create an absence of electrons in the lattice. The impurity levels and the proximity of the doped regions are set out in a lithographic manufacturing process. In addition to doped silicon regions, layers of insulating silicon dioxide glass (SiO2) and conducting layers of polycrystalline silicon and aluminum are deposited to complete the MOSFET structure. MOS transistors work by forming an electrically conductive channel between the source and drain terminals. When a voltage is applied to the control gate, an electric field causes a thin negatively charged channel to form at the boundary of the SiO2 and between the source and drain regions. When the N-channel is present, electricity is easily conducted from the source to the drain terminals. When the control voltage is removed, the N-channel disappears and no conduction takes place. The MOSFET operates like a switch, either in the on or off state.

In addition to the control gate, there is a secondary floating gate which is not electrically connected to the rest of the transistor. The voltage at the control gate required for N-channel formation can be changed by modifying the charge stored on the floating gate. Even though there is no electrical connection to the floating gate, electric charge can be put in to and taken off of the floating gate. A quantum physical process called Fowler-Nordheim tunneling coaxes electrons through the insulation between the floating gate and the P-well. When electric charge is removed from the floating gate, the cell is considered in an erased state. When electric charge is added to the floating gate, the cell is considered in the programmed state. A charge that has been added to the floating gate will remain for a long period of time. It is this process of adding, removing and storing electric charge on the floating gate that turns the MOSFET into a memory cell. Erasing the contents of a memory cell is done by placing a high voltage on the silicon substrate while holding the control gate at zero. The electrons stored in the floating gate tunnel through the oxide barrier into the positive substrate. Thousands of memory cells are etched onto a common section of the substrate, forming a single block of memory. All of the memory cells in the block are

simultaneously erased when the substrate is “flashed” to a positive voltage. An erased memory cell will allow N-channel formation at a low control gate voltage because all of the charge in the floating gate has been removed. This is referred to as logic level “1” in a single-level cell (SLC) flash memory cell.

The cell is programmed by placing a high voltage on the control gate while holding the source and drain regions at zero. The high electric field causes the N-channel to form and allows electrons to tunnel through the oxide barrier into the floating gate. Programming the memory cells is performed one word at a time and usually an entire page is programmed in a single operation. A programmed memory cell inhibits the control gate from forming an N-channel at normal voltages because of the negative charge stored on the floating gate. To form the N-channel in the substrate, the control gate voltage must be raised to a higher level. This is referred to as logic level “0” in an SLC flash memory cell.

References https://www.intel.com/pressroom/.html https://www.intel.com/go/ssd/.html https://www.physorg.com/news/.html https://www.storageview.com/.html www. ieeexplore.ieee.org

Wireless Charging Of Mobile Phones Using Microwaves Published on Dec 06, 2015

Abstract With mobile phones becoming a basic part of life, the recharging of mobile phone batteries has always been a problem. The mobile phones vary in their talk time and battery standby according to their manufacture and batteries. All these phones irrespective of their manufacturer and batteries have to be put to recharge after the battery has drained out. The main objective of this current proposal is to make the recharging of the mobile phones independent of their manufacturer and battery make. In this paper a new proposal has been made so as to make the recharging of the mobile phones is done automatically as you talk in your mobile phone! This is done by use of microwaves. The microwave signal is transmitted from the transmitter along with the message signal using special kind of antennas called slotted wave guide antenna at a frequency is 2.45 GHz. There are minimal additions, which have to be made in the mobile handsets, which are the addition of a sensor, a Rectenna, and a filter. With the above setup, the need for separate chargers for mobile phones is eliminated and makes charging universal. Thus the more you talk, the more is your mobile phone charged! With this proposal the manufacturers would be able to remove the talk time and battery stand by from their phone specifications. Introduction of Wireless Charging Of Mobile Phones Using Microwaves The basic addition to the mobile phone is going to be the rectenna. A rectenna is a rectifying antenna, a special type of antenna that is used to directly convert microwave energy into DC electricity. Its elements are usually arranged in a mesh pattern, giving it a distinct appearance from most antennae. A simple rectenna can be constructed from a Schottky diode placed between antenna dipoles. The diode rectifies the current induced in the antenna by the microwaves. Rectenna are highly efficient at converting microwave energy to electricity. In laboratory environments, efficiencies above 90% have been observed with regularity. Some experimentation has been done with inverse rectenna, converting electricity into microwave energy, but efficiencies are much lower--only in the area of 1%. With the advent of nanotechnology and MEMS the size of these devices can be brought down to molecular level. It has been theorized that similar devices, scaled down to the proportions used in nanotechnology, could be used to convert light into electricity at much greater efficiencies than what is currently possible with solar cells. This type of device is called an optical rectenna. Theoretically, high efficiencies can be maintained as the device shrinks, but experiments funded by the United States National Renewable energy Laboratory have so far only obtained roughly 1% efficiency while using infrared light. Another important part of our receiver circuitry is a simple sensor.

Receiver Design : The basic addition to the mobile phone is going to be the rectenna. A rectenna is a rectifying antenna, a special type of antenna that is used to directly convert microwave energy into DC electricity.

Rectifies received microwaves into DC current a rectenna comprises of a mesh of dipoles and diodes for absorbing microwave energy from a transmitter and converting it into electric power. Its elements are usually arranged in a mesh pattern, giving it a distinct appearance from most antennae. A simple rectenna can be constructed from a Schottky diode placed between antenna dipoles as shown in Fig... The diode rectifies the current induced in the antenna by the microwaves. Rectenna are highly efficient at converting microwave energy to electricity. In laboratory environments, efficiencies above 90% have been observed with regularity. In future rectennass will be used to generate large-scale power from microwave beams delivered from orbiting SPS satellites. The sensor circuitry is a simple circuit, which detects if the mobile phone receives any message signal. This is required, as the phone has to be charged as long as the is talking. Thus a simple F to V converter would serve our purpose. In India the operating frequency of the mobile phone operators is generally 900MHz or 1800MHz for the GSM system for mobile communication.

Microwave Superconductivity Published on Dec 06, 2015

Abstract Superconductivity is a phenomenon occurring in certain materials generally at very low temperatures, characterized by exactly zero electrical resistance and the exclusion of the interior magnetic field (the Meissner effect). It was discovered by Heike Kamerlingh Onnes in 1911. Applying the principle of S uper conductivity in microwave and millimeter-wave (mm-wave) regions, components with superior performance can be fabricated. Major problem during the earlier days was the that the cryogenic burden has been perceived as too great compared to the performance advantage that could be realized. There were very specialized applications, such as low-noise microwave and mm-wave mixers and detectors, for the highly demanding radio astronomy applications where the performance gained was worth the effort and complexity. With the discovery of high temperature superconductors like copper oxide, rapid progress was made in the field of microwave superconductivity.

Microwave Superconductivity According to BCS theory cooper pairs are formed during superconducting state and it is having energy slightly less than the normal electrons.so there exist a superconducting energy gap between normal electrons and cooper pairs. The band gap 'E' related to transition temperature by relation, E (at t=0K) =3.52*Kb*Tc Where Kb - Boltzman's constant Tc - Critical temperature and 3.52 is a constant for ideal superconductor and may vary from 3.2 to 3.6 for most superconductors. If a microwave or a millimeter wave photon with energy greater than superconducting energy gap incident on a sample and is absorbed by the cooper pair, it will be broken with two normal electron created above the energy gap and zero resistance property is lost by material. This property is shown in fig below. For ideal with a transition temperature of Tc = 1K, the frequency of the mm wave photon with energy equal to superconducting energy gap at T=0K would be about 73GHz. For practical superconductors the photon energy corresponding to energy gap would scale with Tc. For niobium (Tc=9.2K) the most common material in LTS devices and circuits, the frequency of radiation corresponding to energy gap is about 670GHz. The zero resistance property of the superconductor is true for dc (f=0). For finite frequencies there are finite but usually very small electrical losses. The origin of these losses at non zero frequency is due to the presence of two type of charge carriers in the superconductor. Although cooper pairs move without resistance, the carriers in normal state, those above energy gap behave as electrons in normal conductor. As long as the operating frequency is below energy gap the equivalent circuit for the superconductor is simply the parallel combination of resistor and inductor, where resistor

indicate normal electrons and inductor the cooper pairs. These two carriers contribute separately to the screening of fields. The characteristic decay length of fields into a super conductor as determined by cooper pair current is superconducting penetration depth. The penetration depth get larger with increased temperature but only slightly close to Tc

Meissner Effect: The Meissner effect (also known as the Meissner-Ochsenfeld effect) is the expulsion of a magnetic field from a superconductor. Walther Meissner and Robert Ochsenfeld discovered the phenomenon in 1933 by measuring the magnetic field distribution outside tin and lead samples. The samples, in the presence of an applied magnetic field, were cooled below what is called their superconducting transition temperature. Below the transition temperature the samples cancelled all magnetic field inside, which means they became perfectly diamagnetic. They detected this effect only indirectly; because the magnetic flux is conserved by a superconductor, when the interior field decreased the exterior field increased.

Fig2: meissner effect The meissner experiment demonstrated for the first time that superconductors were more than just perfect conductors and provided a uniquely defining property of the superconducting state. In fig2 shown the first one represents the ing of magnetic field when T>Tc and second one shows meissner effect at T

2.2 High temperature superconductivity (HTS): The major problem associated with superconductivity in earlier days was the cryogenic burden or the difficulty in maintaining temperature below the critical temperature. High-temperature superconductors (abbreviated high-Tc or HTS) are materials that have a superconducting transition temperature (Tc) above 30 K, which was thought (1960-1980) to be the highest theoretically allowed Tc. The first high-Tc superconductor was discovered in 1986 by Karl Müller and Johannes Bednorz, for which they were awarded the Nobel Prize in Physics in 1987. The interest towards superconductivity greatly increased after the discovery in 1986 of a class of copper oxide material that shows superconductivity at temperature near 40K.Rapid progress was made and the critical temperature pushed to approximately 90-120K for these oxide-based high temperature superconductors.

Later hts was discovered in other materials like Lanthanum based cuprate perovskite material with transition temperature of 35K, yttrium based YBCO with transition temperature of 92K which was important because liquid nitrogen could then be used as a refrigerant. Later highest temperature superconductor was a ceramic material consisting of thallium, mercury, copper, barium, calcium, and oxygen, with Tc=138 K ,iron based family of superconductor, bismuth strontium calcium oxide or BSSCO with Tc=107K etc.

Challenges in the Migration to 4G Published on Nov 23, 2015

Abstract Second-generation (2G) mobile systems were very successful in the previous decade. Their success prompted the development of third generation (3G) mobile systems. While 2G systems such as GSM, IS-95, and cdmaOne were designed to carry speech and low-bit-rate data, 3G systems were designed to provide higher-data-rate services. During the evolution from 2G to 3G, a range of wireless systems, including GPRS, IMT-2000, Bluetooth, WLAN, and HiperLAN, have been developed. All these systems were designed independently, targeting different service types, data rates, and s. As all these systems have their own merits and shortcomings, there is no single system that is good enough to replace all the other technologies. Instead of putting efforts into developing new radio interfaces and technologies for 4G systems, which some researchers are doing, we believe establishing 4G systems that integrate existing and newly developed wireless systems is a more feasible option. Researchers are currently developing frameworks for future 4G networks. Different research programs, such as Mobile VCE, MIRAI, and DoCoMo, have their own visions on 4G features and implementations. Some key features (mainly from 's point of view) of 4G networks are stated as follows: " High usability: anytime, anywhere, and with any technology " for multimedia services at low transmission cost " Personalization " Integrated services

First, 4G networks are all IP based heterogeneous networks that allow s to use any system at any time and anywhere. s carrying an integrated terminal can use a wide range of applications provided by multiple wireless networks. Second, 4G systems provide not only telecommunications services, but also data and multimedia services. To multimedia services, high-data-rate services with good system reliability will be provided. At the same time, a low per-bit transmission cost will be maintained. Third, personalized service will be provided by this new-generation network. It is expected that when 4G services are launched, s in widely different locations, occupations, and economic classes will use the services. In order to meet the demands of these diverse s, service providers should design personal and customized services for them. Finally, 4G systems also provide facilities for integrated services. s can use multiple services from any service provider at the same time. Just imagine a 4G mobile , Mary, who is looking for information on movies shown in nearby cinemas. Her mobile may simultaneously connect to different wireless systems. These wireless systems may include a Global Positioning System (GPS) (for tracking her current location), a wireless LAN (for receiving previews of the movies in nearby cinemas), and a code-division multiple access (CDMA) (for making a telephone call to one of the cinemas). In this example Mary is actually using multiple wireless services that differ in quality of service (QoS) levels, security policies, device settings, charging methods and applications. It will be a significant revolution if such highly integrated services are made possible in 4G mobile applications. To migrate current systems to 4G with the features mentioned above, we have to face a number of challenges. In this article these challenges are highlighted and grouped into various research areas. An overview of the challenges in future heterogeneous systems will be provided. Each area of challenges will be examined in detail. The article is then conclude

Radio Frequency Identification Device (RFID) Published on Dec 12, 2015

Abstract Radio frequency identification (RFID) is a less form of automatic identification and data capture. Dating back to World War II, RFID transponders were used to identify friendly aircraft. The RFID system consists of a reader, transponder, and antenna utilizing several frequency ranges. Over 40 million RFID tags will be used in 1999 with sales projected to break the one billion-dollar mark before 2003 (Frost & Sullivan, 1997). Radio frequency identification is used in access control, asset control, and animal identification. The advantages of RFID are the capability for multiple reads, ability to be used in almost any environment, and the accuracy. The Automatic Identification Manufacturers, International Standards Organization, and the American National Standards Institute are currently developing standards. Barcodes have been developed in the railroad business to keep track of the various cars. Out of this system of identification grew the U.P.C. (Universal Product Code) which is now used in almost all manufactured goods. UPC is used to store the manufacturer code as well as the product code in a form that can be easily read by various scanners - even from a distance. But there are limits to the

use of barcodes. There must be a direct line of sight between the reader and the code. The barcode can be obscured, for example by paint. One only has read-access to the data, i.e., one cannot add new data without adding another label. This is the point where a relatively new technology comes in: RFID (Radio Frequency IDentification). In RFID electronic chips are used to store data that can be broadcast via radio waves to the reader, eliminating the need for a direct line of sight and making it possible for "tags" to be placed anywhere on or in the product. One can even write to tags made of semiconductor chips, thus enabling updating of data. This write function introduces new capabilities, such as the updating of the manufacturing process of the attached item. RFID first appeared in tracking and access applications during the 1980s. These wireless AIDC systems allow for non- reading and are effective in manufacturing and other hostile environments where bar code labels could not survive. RFID has established itself in livestock identification and automated vehicle identification (AVI) systems because of its ability to track moving objects. To understand and appreciate the capabilities of RFID systems it is necessary to consider their constituent parts. It is also necessary to consider the data flow requirements that influence the choice of systems and the practicalities of communicating across the air interface. By considering the system components and their function within the data flow chain it is possible to grasp most of the important issues that influence the effective application of RFID. The RFID reader is designed for fast and easy system integration without losing performance, functionality or security. The RFID reader consists of a real time processor, operating system, virtual portable memory, and transmitter/receiver unit in one small self-contained module that is easily installed in the ceiling or in any other convenient location.