In electronics, an integrated circuit - Free Essay Example

In electronics, an integrated circuit (also known as IC, microcircuit, microchip, silicon chip, or chip) is a miniaturized electronic circuit (consisting mainly of semiconductor devices, as well as passive components) that has been manufactured in the surface of a thin substrate of semiconductor material. Integrated circuits are used in almost all electronic equipment in use today and have revolutionized the world of electronics. A hybrid integrated circuit is a miniaturized electronic circuit constructed of individual semiconductor devices, as well as passive components, bonded to a substrate or circuit board. Contents | |[hide] | |1 Introduction | |2 Invention | |3 Generations | |3. 1 SSI, MSI and LSI | |3. 2 VLSI | |3. ULSI, WSI, SOC and 3D-IC | |4 Advances in integrated circuits | |5 Popularity of ICs | |6 Classification | |7 Manufacturing | |7. 1 Fabrication | |7. 2 Packaging | |7. Chip labeling and manufacture date | |8 Legal protection of semiconductor chip layouts | | 9 Other developments | |10 Silicon labelling and graffiti | |11 Key industrial and academic data | |11. 1 Notable ICs | |11. 2 Manufacturers | |11. VLSI conferences | |11. 4 VLSI journals | |12 See also | |13 References | |14 Further reading | |15 External links | Introduction [pic] [pic] Synthetic detail of an integrated circuit through four layers of planarized copper interconnect, down to the polysilicon (pink), wells (greyish), and substrate (green). Integrated circuits were made possible by experimental discoveries which showed that semiconductor devices could perform the functions of vacuum tubes and by mid-20th-century technology advancements in semiconductor device fabrication. The integration of large numbers of tiny transistors into a small chip was an enormous improvement over the manual assembly of circuits using electronic components. The integrated circuits mass production capability, reliability, and building-block approach to circuit design ensured the rapid adopt ion of standardized ICs in place of designs using discrete transistors. There are two main advantages of ICs over discrete circuits: cost and performance. Cost is low because the chips, with all their components, are printed as a unit by photolithography and not constructed as one transistor at a time. Furthermore, much less material is used to construct a circuit as a packaged IC die than as a discrete circuit. Performance is high since the components switch quickly and consume little power (compared to their discrete counterparts) because the components are small and close together. As of 2006, chip areas range from a few square millimeters to around 350  mm2, with up to 1 million transistors per mm2. [edit] Invention [pic] [pic] Jack Kilbys original integrated circuit The idea of the integrated circuit was conceived by a radar scientist working for the Royal Radar Establishment of the British Ministry of Defence, Geoffrey W. A. Dummer (1909–2002), who published it at the Symposium on Progress in Quality Electronic Components in Washington, D. C. on May 7, 1952. [1] He gave many symposia publicly to propagate his ideas. Dummer unsuccessfully attempted to build such a circuit in 1956. Jack Kilby recorded his initial ideas concerning the integrated circuit in July 1958 and successfully demonstrated the first working integrated circuit on September 12, 1958. [2] In his patent application of February 6, 1959, Kilby described his new device as â€Å"a body of semiconductor material wherein all the components of the electronic circuit are completely integrated. † [3] Kilby won the 2000 Nobel Prize in Physics for his part of the invention of the integrated circuit. [4] Robert Noyce also came up with his own idea of an integrated circuit half a year later than Kilby. Noyces chip solved many practical problems that Kilbys had not. Noyces chip, made at Fairchild Semiconductor, was made of silicon, whereas Kilbys chip was made of germanium. Early developments of the integrated circuit go back to 1949, when the German engineer Werner Jacobi (Siemens AG) filed a patent for an integrated-circuit-like semiconductor amplifying device [5] showing five transistors on a common substrate arranged in a 2-stage amplifier arrangement. Jacobi discloses small and cheap hearing aids as typical industrial applications of his patent. A commercial use of his patent has not been reported. A precursor idea to the IC was to create small ceramic squares (wafers), each one containing a single miniaturized component. Components could then be integrated and wired into a bidimensional or tridimensional compact grid. This idea, which looked very promising in 1957, was proposed to the US Army by Jack Kilby, and led to the short-lived Micromodule Program (similar to 1951s Project Tinkertoy). [6] However, as the project was gaining momentum, Kilby came up with a new, revolutionary design: the IC. Robert Noyce credited Kurt Lehovec of Sprague Electric for the principle of p-n junction isolation caused by the action of a biased p-n junction (the diode) as a key concept behind the IC. [7] See: Other variations of vacuum tubes for precursor concepts such as the Loewe 3NF. enerations [edit] SSI, MSI and LSI The first integrated circuits contained only a few transistors. Called Small-Scale Integration (SSI), digital circuits containing transistors numbering in the tens provided a few logic gates for example, while early linear ICs such as the Plessey SL201 or the Philips TAA320 had as few as two transistors. The term Large Scale Integration was first used by IBM scientist Rolf Landauer when describing the theoretical concept, from there came the terms for SSI, MSI, VLSI, and ULSI. SSI circuits were crucial to early aerospace projects, and vice-versa. Both the Minuteman missile and Apollo program needed lightweight digital computers for their inertial guidance systems; the Apollo guidance computer led and motivated the int egrated-circuit technology[citation needed], while the Minuteman missile forced it into mass-production. These programs purchased almost all of the available integrated circuits from 1960 through 1963, and almost alone provided the demand that funded the production improvements to reduce production costs from $1000/circuit (in 1960 dollars) to merely $25/circuit (in 1963 dollars). [citation needed] They began to appear in consumer products at the turn of the decade, a typical application being FM inter-carrier sound processing in television receivers. The next step in the development of integrated circuits, taken in the late 1960s, introduced devices which contained hundreds of transistors on each chip, called Medium-Scale Integration (MSI). They were attractive economically because while they cost little more to produce than SSI devices, they allowed more complex systems to be produced using smaller circuit boards, less assembly work (because of fewer separate components), an d a number of other advantages. Further development, driven by the same economic factors, led to Large-Scale Integration (LSI) in the mid 1970s, with tens of thousands of transistors per chip. Integrated circuits such as 1K-bit RAMs, calculator chips, and the first microprocessors, that began to be manufactured in moderate quantities in the early 1970s, had under 4000 transistors. True LSI circuits, approaching 10000 transistors, began to be produced around 1974, for computer main memories and second-generation microprocessors. [edit] VLSI Main article: Very-large-scale integration [pic] [pic] Upper interconnect layers on an Intel 80486DX2 microprocessor die. The final step in the development process, starting in the 1980s and continuing through the present, was very large-scale integration (VLSI). The development started with hundreds of thousands of transistors in the early 1980s, and continues beyond several billion transistors as of 2009. There was no single breakthrough t hat allowed this increase in complexity, though many factors helped. Manufacturers moved to smaller rules and cleaner fabs, so that they could make chips with more transistors and maintain adequate yield. The path of process improvements was summarized by the International Technology Roadmap for Semiconductors (ITRS). Design tools improved enough to make it practical to finish these designs in a reasonable time. The more energy efficient CMOS replaced NMOS and PMOS, avoiding a prohibitive increase in power consumption. Better texts such as the landmark textbook by Mead and Conway helped schools educate more designers, among other factors. In 1986 the first one megabit RAM chips were introduced, which contained more than one million transistors. Microprocessor chips passed the million transistor mark in 1989 and the billion transistor mark in 2005[8]. The trend continues largely unabated, with chips introduced in 2007 containing tens of billions of memory transistors [9]. [edit] U LSI, WSI, SOC and 3D-IC ULSI, WSI, SOC and 3D-IC To reflect further growth of the complexity, the term ULSI that stands for ultra-large-scale integration was proposed for chips of complexity of more than 1 million transistors. Wafer-scale integration (WSI) is a system of building very-large integrated circuits that uses an entire silicon wafer to produce a single super-chip. Through a combination of large size and reduced packaging, WSI could lead to dramatically reduced costs for some systems, notably massively parallel supercomputers. The name is taken from the term Very-Large-Scale Integration, the current state of the art when WSI was being developed. A system-on-a-chip (SoC or SOC) is an integrated circuit in which all the components needed for a computer or other system are included on a single chip. The design of such a device can be complex and costly, and building disparate components on a single piece of silicon may compromise the efficiency of some elements. However , these drawbacks are offset by lower manufacturing and assembly costs and by a greatly reduced power budget: because signals among the components are kept on-die, much less power is required (see Packaging). A three-dimensional integrated circuit (3D-IC) has two or more layers of active electronic components that are integrated both vertically and horizontally into a single circuit. Communication between layers uses on-die signaling, so power consumption is much lower than in equivalent separate circuits. Judicious use of short vertical wires can substantially reduce overall wire length for faster operation Advances in integrated circuits [pic] [pic] The die from an Intel 8742, an 8-bit microcontroller that includes a CPU running at 12 MHz, 128 bytes of RAM, 2048 bytes of EPROM, and I/O in the same chip. Among the most advanced integrated circuits are the microprocessors or cores, which control everything from computers to cellular phones to digital microwave ovens. Digital m emory chips and ASICs are examples of other families of integrated circuits that are important to the modern information society. While the cost of designing and developing a complex integrated circuit is quite high, when spread across typically millions of production units the individual IC cost is minimized. The performance of ICs is high because the small size allows short traces which in turn allows low power logic (such as CMOS) to be used at fast switching speeds. ICs have consistently migrated to smaller feature sizes over the years, allowing more circuitry to be packed on each chip. This increased capacity per unit area can be used to decrease cost and/or increase functionality—see Moores law which, in its modern interpretation, states that the number of transistors in an integrated circuit doubles every two years. In general, as the feature size shrinks, almost everything improves—the cost per unit and the switching power consumption go down, and the speed goes up. However, ICs with nanometer-scale devices are not without their problems, principal among which is leakage current (see subthreshold leakage for a discussion of this), although these problems are not insurmountable and will likely be solved or at least ameliorated by the introduction of high-k dielectrics. Since these speed and power consumption gains are apparent to the end user, there is fierce competition among the manufacturers to use finer geometries. This process, and the expected progress over the next few years, is well described by the International Technology Roadmap for Semiconductors (ITRS). edit] Popularity of ICs Only a half century after their development was initiated, integrated circuits have become ubiquitous. Computers, cellular phones, and other digital appliances are now inextricable parts of the structure of modern societies. That is, modern computing, communications, manufacturing and transport systems, including the Internet, all depend on the exi stence of integrated circuits. Classification [pic] [pic] A CMOS 4000 IC in a DIP Integrated circuits can be classified into analog, digital and mixed signal (both analog and digital on the same chip). Digital integrated circuits can contain anything from one to millions of logic gates, flip-flops, multiplexers, and other circuits in a few square millimeters. The small size of these circuits allows high speed, low power dissipation, and reduced manufacturing cost compared with board-level integration. These digital ICs, typically microprocessors, DSPs, and micro controllers work using binary mathematics to process one and zero signals. Analog ICs, such as sensors, power management circuits, and operational amplifiers, work by processing continuous signals. They perform functions like amplification, active filtering, demodulation, mixing, etc. Analog ICs ease the burden on circuit designers by having expertly designed analog circuits available instead of designing a difficult a nalog circuit from scratch. ICs can also combine analog and digital circuits on a single chip to create functions such as A/D converters and D/A converters. Such circuits offer smaller size and lower cost, but must carefully account for signal interference. Manufacturing [edit] Fabrication Main article: Semiconductor fabrication [pic] [pic] Rendering of a small standard cell with three metal layers (dielectric has been removed). The sand-colored structures are metal interconnect, with the vertical pillars being contacts, typically plugs of tungsten. The reddish structures are polysilicon gates, and the solid at the bottom is the crystalline silicon bulk. [pic] [pic] Schematic structure of a CMOS chip, as built in the early 2000s. The graphic shows LDD-MISFETs on an SOI substrate with five metallization layers and solder bump for flip-chip bonding. It also shows the section for FEOL (front-end of line), BEOL (back-end of line) and first parts of back-end process. The semiconduc tors of the periodic table of the chemical elements were identified as the most likely materials for a solid state vacuum tube by researchers like William Shockley at Bell Laboratories starting in the 1930s. Starting with copper oxide, proceeding to germanium, then silicon, the materials were systematically studied in the 1940s and 1950s. Today, silicon monocrystals are the main substrate used for integrated circuits (ICs) although some III-V compounds of the periodic table such as gallium arsenide are used for specialized applications like LEDs, lasers, solar cells and the highest-speed integrated circuits. It took decades to perfect methods of creating crystals without defects in the crystalline structure of the semiconducting material. Semiconductor ICs are fabricated in a layer process which includes these key process steps: †¢ Imaging †¢ Deposition †¢ Etching The main process steps are supplemented by doping and cleaning. Mono-crystal silicon wafers (or for sp ecial applications, silicon on sapphire or gallium arsenide wafers) are used as the substrate. Photolithography is used to mark different areas of the substrate to be doped or to have polysilicon, insulators or metal (typically aluminium) tracks deposited on them. Integrated circuits are composed of many overlapping layers, each defined by photolithography, and normally shown in different colors. Some layers mark where various dopants are diffused into the substrate (called diffusion layers), some define where additional ions are implanted (implant layers), some define the conductors (polysilicon or metal layers), and some define the connections between the conducting layers (via or contact layers). All components are constructed from a specific combination of these layers. In a self-aligned CMOS process, a transistor is formed wherever the gate layer (polysilicon or metal) crosses a diffusion layer. †¢ Capacitive structures, in form very much like the parallel conducting plate s of a traditional electrical capacitor, are formed according to the area of the plates, with insulating material between the plates. Capacitors of a wide range of sizes are common on ICs. †¢ Meandering stripes of varying lengths are sometimes used to form on-chip resistors, though most logic circuits do not need any resistors. The ratio of the length of the resistive structure to its width, combined with its sheet resistivity, determines the resistance. †¢ More rarely, inductive structures can be built as tiny on-chip coils, or simulated by gyrators. Since a CMOS device only draws current on the transition between logic states, CMOS devices consume much less current than bipolar devices. A random access memory is the most regular type of integrated circuit; the highest density devices are thus memories; but even a microprocessor will have memory on the chip. (See the regular array structure at the bottom of the first image. Although the structures are intricate  œ with widths which have been shrinking for decades – the layers remain much thinner than the device widths. The layers of material are fabricated much like a photographic process, although light waves in the visible spectrum cannot be used to expose a layer of material, as they would be too large for the features. Thus photons of higher frequencies (typically ultraviolet) are used to create the patterns for each layer. Because each feature is so small, electron microscopes are essential tools for a process engineer who might be debugging a fabrication process. Each device is tested before packaging using automated test equipment (ATE), in a process known as wafer testing, or wafer probing. The wafer is then cut into rectangular blocks, each of which is called a die. Each good die (plural dice, dies, or die) is then connected into a package using aluminium (or gold) bond wires which are welded and/or Thermosonic Bonded to pads, usually found around the edge of the die. Aft er packaging, the devices go through final testing on the same or similar ATE used during wafer probing. Test cost can account for over 25% of the cost of fabrication on lower cost products, but can be negligible on low yielding, larger, and/or higher cost devices. As of 2005, a fabrication facility (commonly known as a semiconductor lab) costs over a billion US Dollars to construct[10], because much of the operation is automated. The most advanced processes employ the following techniques: †¢ The wafers are up to 300  mm in diameter (wider than a common dinner plate). †¢ Use of 65 nanometer or smaller chip manufacturing process. Intel, IBM, NEC, and AMD are using 45 nanometers for their CPU chips. IBM and AMD are in development of a 45  nm process using immersion lithography. †¢ Copper interconnects where copper wiring replaces aluminium for interconnects. †¢ Low-K dielectric insulators. †¢ Silicon on insulator (SOI) †¢ Strained silicon in a process used by IBM known as strained silicon directly on insulator (SSDOI) Packaging Main article: Integrated circuit packaging [pic] [pic] Early USSR made integrated circuit The earliest integrated circuits were packaged in ceramic flat packs, which continued to be used by the military for their reliability and small size for many years. Commercial circuit packaging quickly moved to the dual in-line package (DIP), first in ceramic and later in plastic. In the 1980s pin counts of VLSI circuits exceeded the practical limit for DIP packaging, leading to pin grid array (PGA) and leadless chip carrier (LCC) packages. Surface mount packaging appeared in the early 1980s and became popular in the late 1980s, using finer lead pitch with leads formed as either gull-wing or J-lead, as exemplified by small-outline integrated circuit a carrier which occupies an area about 30 – 50% less than an equivalent DIP, with a typical thickness that is 70% less. This package has gull wing l eads protruding from the two long sides and a lead spacing of 0. 050  inches. In the late 1990s, PQFP and TSOP packages became the most common for high pin count devices, though PGA packages are still often used for high-end microprocessors. Intel and AMD are currently transitioning from PGA packages on high-end microprocessors to land grid array (LGA) packages. Ball grid array (BGA) packages have existed since the 1970s. Flip-chip Ball Grid Array packages, which allow for much higher pin count than other package types, were developed in the 1990s. In an FCBGA package the die is mounted upside-down (flipped) and connects to the package balls via a package substrate that is similar to a printed-circuit board rather than by wires. FCBGA packages allow an array of input-output signals (called Area-I/O) to be distributed over the entire die rather than being confined to the die periphery. Traces out of the die, through the package, and into the printed circuit board have very diffe rent electrical properties, compared to on-chip signals. They require special design techniques and need much more electric power than signals confined to the chip itself. When multiple dies are put in one package, it is called SiP, for System In Package. When multiple dies are combined on a small substrate, often ceramic, its called an MCM, or Multi-Chip Module. The boundary between a big MCM and a small printed circuit board is sometimes fuzzy. [edit] Chip labeling and manufacture date Most integrated circuits large enough to include identifying information include four common sections: the manufacturers name or logo, the part number, a part production batch number and/or serial number, and a four-digit code that identifies when the chip was manufactured. Extremely small surface mount technology parts often bear only a number used in a manufacturers lookup table to find the chip characteristics. The manufacturing date is commonly represented as a two-digit year followed by a two-digit week code, such that a part bearing the code 8341 was manufactured in week 41 of 1983, or approximately in October 1983. Packaging Main article: Integrated circuit packaging [pic] [pic] Early USSR made integrated circuit The earliest integrated circuits were packaged in ceramic flat packs, which continued to be used by the military for their reliability and small size for many years. Commercial circuit packaging quickly moved to the dual in-line package (DIP), first in ceramic and later in plastic. In the 1980s pin counts of VLSI circuits exceeded the practical limit for DIP packaging, leading to pin grid array (PGA) and leadless chip carrier (LCC) packages. Surface mount packaging appeared in the early 1980s and became popular in the late 1980s, using finer lead pitch with leads formed as either gull-wing or J-lead, as exemplified by small-outline integrated circuit a carrier which occupies an area about 30 – 50% less than an equivalent DIP, with a typical thi ckness that is 70% less. This package has gull wing leads protruding from the two long sides and a lead spacing of 0. 050  inches. In the late 1990s, PQFP and TSOP packages became the most common for high pin count devices, though PGA packages are still often used for high-end microprocessors. Intel and AMD are currently transitioning from PGA packages on high-end microprocessors to land grid array (LGA) packages. Ball grid array (BGA) packages have existed since the 1970s. Flip-chip Ball Grid Array packages, which allow for much higher pin count than other package types, were developed in the 1990s. In an FCBGA package the die is mounted upside-down (flipped) and connects to the package balls via a package substrate that is similar to a printed-circuit board rather than by wires. FCBGA packages allow an array of input-output signals (called Area-I/O) to be distributed over the entire die rather than being confined to the die periphery. Traces out of the die, through the pac kage, and into the printed circuit board have very different electrical properties, compared to on-chip signals. They require special design techniques and need much more electric power than signals confined to the chip itself. When multiple dies are put in one package, it is called SiP, for System In Package. When multiple dies are combined on a small substrate, often ceramic, its called an MCM, or Multi-Chip Module. The boundary between a big MCM and a small printed circuit board is sometimes fuzzy. [edit] Chip labeling and manufacture date Most integrated circuits large enough to include identifying information include four common sections: the manufacturers name or logo, the part number, a part production batch number and/or serial number, and a four-digit code that identifies when the chip was manufactured. Extremely small surface mount technology parts often bear only a number used in a manufacturers lookup table to find the chip characteristics. The manufacturing date i s commonly represented as a two-digit year followed by a two-digit week code, such that a part bearing the code 8341 was manufactured in week 41 of 1983, or approximately in October 1983. Legal protection of semiconductor chip layouts Main article: Semiconductor Chip Protection Act of 1984 Prior to 1984, it was not necessarily illegal to produce a competing chip with an identical layout. As the legislative history for the Semiconductor Chip Protection Act of 1984, or SCPA, explained, patent and copyright protection for chip layouts, or topographies, were largely unavailable. This led to considerable complaint by U. S. chip manufacturers—notably, Intel, which took the lead in seeking legislation, along with the Semiconductor Industry Association (SIA)against what they termed chip piracy. A 1984 addition to US law, the SCPA, made all so-called mask works (i. e. , chip topographies) protectable if registered with the U. S. Copyright Office. Similar rules apply in most oth er countries that manufacture ICs. (This is a simplified explanation see SCPA for legal details. ) [edit] Other developments In the 1980s, programmable integrated circuits were developed. These devices contain circuits whose logical function and connectivity can be programmed by the user, rather than being fixed by the integrated circuit manufacturer. This allows a single chip to be programmed to implement different LSI-type functions such as logic gates, adders and registers. Current devices named FPGAs (Field Programmable Gate Arrays) can now implement tens of thousands of LSI circuits in parallel and operate up to 550  MHz. The techniques perfected by the integrated circuits industry over the last three decades have been used to create microscopic machines, known as MEMS. These devices are used in a variety of commercial and military applications. Example commercial applications include DLP projectors, inkjet printers, and accelerometers used to deploy automobile airbags. In the past, radios could not be fabricated in the same low-cost processes as microprocessors. But since 1998, a large number of radio chips have been developed using CMOS processes. Examples include Intels DECT cordless phone, or Atheross 802. 11 card. Future developments seem to follow the multi-core multi-microprocessor paradigm, already used by the Intel and AMD dual-core processors. Intel recently unveiled a prototype, not for commercial sale chip that bears a staggering 80 microprocessors. Each core is capable of handling its own task independently of the others. This is in response to the heat-versus-speed limit that is about to be reached using existing transistor technology. This design provides a new challenge to chip programming. Parallel programming languages such as the open-source X10 programming language are designed to assist with this task. [11] Silicon labelling and graffiti To allow identification during production most silicon chips will have a serial number in one corner. It is also common to add the manufactuers logo. Ever since ICs were created, some chip designers have used the silicon surface area for surreptitious, non-functional images or words. These are sometimes referred to as Chip Art, Silicon Art, Silicon Graffiti or Silicon Doodling. [edit] Key industrial and academic data |[pic] |The lists in this article may contain items that are not notable, encyclopedic, or helpful. Please help out by removing| | |such elements and incorporating appropriate items into the main body of the article. (January 2008) | [edit] Notable ICs †¢ The 555 common multivibrator sub-circuit (common in electronic timing circuits) †¢ The 741 operational amplifier †¢ 7400 series TTL logic building blocks 4000 series, the CMOS counterpart to the 7400 series (see also: 74HC00 series) †¢ Intel 4004, the worlds first microprocessor, which led to the famous 8080 CPU and then the IBM PCs 8088, 80286, 486 etc. †¢ The MOS Technology 6502 and Zilog Z80 microprocessors, used in many home computers of the early 1980s †¢ The Motorola 6800 series of computer-related chips, leading to the 68000 and 88000 series (used in some Apple computers). [edit] Manufacturers For a list of microchip manufacturers, see List of integrated circuit manufacturers. VLSI conferences ICM – IEEE International Conference on Microelectronics †¢ ISSCC – IEEE International Solid-State Circuits Conference †¢ CICC – IEEE Custom Integrated Circuit Conference †¢ ISCAS – IEEE International Symposium on Circuits and Systems †¢ VLSI – IEEE International Conference on VLSI Design †¢ DAC – Design Automation Conference †¢ ICCAD – International Conference on Computer-Aided Design †¢ ESSCIRC – European Solid-State Circuits Conference †¢ ISLPED – International Symposium on Low Power Electronics and Design †¢ ISPD – International Symposi um on Physical Design ISQED – International Symposium on Quality Electronic Design †¢ DATE – Design Automation and Test in Europe †¢ ICCD – International Conference on Computer Design †¢ IEDM – IEEE International Electron Devices Meeting †¢ GLSVLSI – IEEE Great Lakes Symposium on VLSI †¢ ASP-DAC – Asia and South Pacific Design Automation Conference †¢ MWSCAS – IEEE Midwest Symposium on Circuits and Systems †¢ ICSVLSI – IEEE Computer Society Annual Symposium on VLSI †¢ IEEE Symposia on VLSI Circuits and Technology [edit] VLSI journals ED – IEEE Transactions on Electron Devices †¢ EDL – IEEE Electron Device Letters †¢ CAD – IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, IEEE web site for this journal †¢ JSSC – IEEE Journal of Solid-State Circuits †¢ VLSI – IEEE Transactions on Very Large Scale Integration (VLSI) Systems †¢ CAS II – IEEE Transactions on Circuits and Systems II: Analog and Digital Signal Processing †¢ SM – IEEE Transactions on Semiconductor Manufacturing †¢ SSE – Solid-State Electronics