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SIMPLE DIGITAL SECURITY SYSTEM

4511 BCD to seven-segment decoder

The 4511 IC is a 16-pin CMOS BCD to seven-segment decoder from the 4000 series. It takes

the binary-coded decimal from a binary counter and decodes it to drive a seven-segment

display .

Pinout

Pinnumber

Name Purpose

1 2s Input for the 2s bit from the binary counter 2 4s Input for the 4s bit from the binary counter

3 LT L amp test - when low, the chip takes all the segments on the display high (to testconnections, etc.)

4 BI Blanking input - when low, the chip does not output to the display - to conserve battery life, for instance

5 LE L atch enable - latches on the current output when high (i.e. the inputs change theoutput when LE is low)

6 8s Input for the 8s bit from the binary counter

7 1s Input for the 1s bit from the binary counter

8 0 V, V DD The connection to the 0 V rail9 E Output for the seven-segment's E input

10 D Output for the seven-segment's D input

11 C Output for the seven-segment's C input

12 B Output for the seven-segment's B input

13 A Output for the seven-segment's A input

14 G Output for the seven-segment's G input

15 F Output for the seven-segment's F input

16 +9 V,VCC

The connection to the +9 V rail

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Seven-segment display

A typical 7-segment LED display component, with decimal point.

A seven-segment display , or seven-segment indicator , is a form of electronic display device for displaying decimal numerals that is an alternative to themore complex dot-matrix displays. Seven-segment displays are widely used in digitalclocks , electronic meters , and other electronic devices for displaying numericalinformation.

Concept and visual structure

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The individual segments of a seven-segment display.

A seven segment display, as its name indicates, is composed of sevenelements. Individually on or off, they can be combined to produce simplifiedrepresentations of the arabic numerals . Often the seven segments are arranged in an

oblique (slanted) arrangement, which aids readability. In most applications, the sevensegments are of nearly uniform shape and size (usually elongated hexagons , thoughtrapezoids and rectangles can also be used), though in the case of adding machines , the vertical segments are longer and more oddly shaped at the ends in an effort tofurther enhance readability.

Each of the numbers 0, 6, 7 and 9 may be represented by two or more differentglyphs on seven-segment displays.

LED-based 7-segment display showing the 16 hex digits.

The seven segments are arranged as a rectangle of two vertical segments oneach side with one horizontal segment on the top, middle, and bottom. Additionally,the seventh segment bisects the rectangle horizontally. There are also fourteen-segment displays and sixteen-segment displays (for full alphanumerics ); however,these have mostly been replaced by dot-matrix displays.

The segments of a 7-segment display are referred to by the letters A to G, asshown to the right, where the optional DP decimal point (an "eighth segment") is usedfor the display of non-integer numbers.

The animation to the left cycles through the common glyphs of the ten decimalnumerals and the six hexadecimal "letter digits" (AF). It is an image sequence of a"LED" display, which is described technology-wise in the following section. Noticethe variation between uppercase and lowercase letters for AF; this is done to obtain aunique, unambiguous shape for each letter (otherwise, a capital D would look identical to an 0 (or less likely O) and a capital B would look identical to an 8).

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Implementations

An incandescent light type early seven-segment display.

A mechanical seven-segment display for displaying automotive fuel prices.

Seven-segment displays may use a liquid crystal display (LCD), arrays of light-emitting diodes (LEDs), or other light-generating or controlling techniques suchas cold cathode gas discharge, vacuum fluorescent , incandescent filaments , andothers. For gasoline price totems and other large signs, vane displays made up of electromagnetically flipped light-reflecting segments (or "vanes") are still commonlyused. An alternative to the 7-segment display in the 1950s through the 1970s was thecold-cathode, neon-lamp-like nixie tube . Starting in 1970, RCA sold a display device

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known as the Numitron that used incandescent filaments arranged into a seven-segment display

In a simple LED package, typically all of the cathodes (negative terminals) or all of the anodes (positive terminals) of the segment LEDs are connected together and

brought out to a common pin; this is referred to as a " common cathode " or " commonanode " device. Hence a 7 segment plus decimal

l point package will only require nine pins (though commercial productstypically contain more pins, and/or spaces where pins would go, in order to matchindustry standard pinouts).

Integrated displays also exist, with single or multiple digits. Some of theseintegrated displays incorporate their own internal decoder, though most do not eachindividual LED is brought out to a connecting pin as described. Multiple-digit LEDdisplays as used in pocket calculators and similar devices used multiplexed displays toreduce the number of IC pins required to control the display. For example, all theanodes of the A segments of each digit position would be connected together and to adriver pin, while the cathodes of all segments for each digit would be connected. Tooperate any particular segment of any digit, the controlling integrated circuit wouldturn on the cathode driver for the selected digit, and the anode drivers for the desiredsegments; then after a short blanking interval the next digit would be selected and newsegments lit, in a sequential fashion. In this manner an eight digit display with sevensegments and a decimal point would require only 8 cathode drivers and 8 anodedrivers, instead of sixty-four drivers and IC pins. Often in pocket calculators the digitdrive lines would be used to scan the keyboard as well, providing further savings;however, pressing multiple keys at once would produce odd results on themultiplexed display.

Seven segment displays can be found in patents as early as 1908 (in U.S.Patent 974,943 , F W Wood invented an 8-segment display, which displayed thenumber 4 using a diagonal bar), but did not achieve widespread use until the advent of LEDs in the 1970s. They are sometimes even used in unsophisticated displays likecardboard "For sale" signs, where the user either applies color to pre-printedsegments, or (spray)paints color through a seven-segment digit template , to composefigures such as product prices or telephone numbers.

For many applications, dot-matrix LCDs have largely superseded LEDdisplays, though even in LCDs 7-segment displays are very common. Unlike LEDs,the shapes of elements in an LCD panel are arbitrary since they are formed on thedisplay by a kind of printing process. In contrast, the shapes of LED segments tend to

be simple rectangles , reflecting the fact that they have to be physically moulded toshape, which makes it difficult to form more complex shapes than the segments of 7-segment displays. However, the high common recognition factor of 7-segmentdisplays, and the comparatively high visual contrast obtained by such displays relativeto dot-matrix digits, makes seven-segment multiple-digit LCD screens very commonon basic calculators .

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Alphabetic display

Main article: Seven-segment display character representations

In addition to the ten numerals, seven segment displays can be used to showletters of the latin , cyrillic and greek alphabets including punctuation , but only fewrepresentations are unambiguous and intuitive at the same time. It is possible torepresent hexadecimal unambiguously by using a mixture of letter cases (AbCdEF istypical) and using a representation of 6 that has the top segment illuminated. This isfrequently used to output hexadecimal codes for troubleshooting purposes. Shortmessages giving status information (e.g. "no disc" on a CD player) are also commonlyrepresented on 7-segment displays. In the case of such messages it is not necessary for every letter to be unambiguous, merely for the words as a whole to be readable

Similar displays with fourteen or sixteen segments are available allowingdecent representations of the alphabet.

Using a restricted range of letters that look like (upside-down) digits, seven-segment displays are commonly used by school children to form words and phrasesusing a technique known as " calculator spelling ".

Numbers to 7-segment-code

A single byte can encode the full state of a 7-segment-display. The most popular bit encodings are gfedcba and abcdefg - both usually assume 0 is off and 1 ison . This table gives the hexadecimal encodings for displaying the digits 0 to F:

Digit gfedcba abcdefg a b c d e f g0 0x3F 0x7E on on on on on on off 1 0x06 0x30 off on on off off off off 2 0x5B 0x6D on on off on on off on3 0x4F 0x79 on on on on off off on4 0x66 0x33 off on on off off on on5 0x6D 0x5B on off on on off on on6 0x7D 0x5F on off on on on on on7 0x07 0x70 on on on off off off off 8 0x7F 0x7F on on on on on on on9 0x6F 0x7B on on on on off on onA 0x77 0x77 on on on off on on on

b 0x7C 0x1F off off on on on on onC 0x39 0x4E on off off on on on off d 0x5E 0x3D off on on on on off onE 0x79 0x4F on off off on on on on

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Integrated circuits

An integrated circuit or monolithic integrated circuit (also referred to asIC , chip , and microchip ) is an electronic circuit manufactured by diffusion of traceelements into the surface of a thin substrate of semiconductor material.

Integrated circuits are used in virtually all electronic equipment today andhave revolutionized the world of electronics. Computers , cellular phones , and other digital appliances are now inextricable parts of the structure of modern societies,made possible by the low cost of production of integrated circuits

Introduction

Synthetic detail of an integrated circuit through four layers of planarizedcopper interconnect, down to the polysilicon (pink), wells (greyish), and substrate(green).

Integrated circuits were made possible by experimental discoveries whichshowed 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 enormousimprovement over the manual assembly of circuits using electronic components . Theintegrated circuit's mass production capability, reliability, and building-block approach to circuit design ensured the rapid adoption 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 aunit by photolithography rather than being constructed one transistor at a time.Furthermore, much less material is used to construct a packaged IC die than a discretecircuit. Performance is high since the components switch quickly and consume little

power (compared to their discrete counterparts) because the components are small and positioned close together. As of 2006, chip areas range from a few square millimetersto around 350 mm 2, with up to 1 million transistors per mm 2 . [citation needed ]

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Terminology

Integrated circuit originally referred to a miniaturized electronic circuit consisting of semiconductor devices , as well as passive components bonded to asubstrate or circuit board, This configuration is now commonly referred to as a hybridintegrated circuit . Integrated circuit has since come to refer to the single-piece circuitconstruction originally known as a monolithic integrated circuit .

Invention

Early developments of the integrated circuit go back to 1949, when theGerman engineer Werner Jacobi (Siemens AG ) filed a patent for an integrated-circuit-like semiconductor amplifying device ] showing five transistors on a commonsubstrate arranged in a 2-stage amplifier arrangement. Jacobi discloses small and

cheap hearing aids as typical industrial applications of his patent. Acommercial use of his patent has not been reported.

The idea of the integrated circuit was conceived by a radar scientist workingfor the Royal Radar Establishment of the British Ministry of Defence , Geoffrey W.A.Dummer (19092002), who published it at the Symposium on Progress in QualityElectronic Components in Washington, D.C. on May 7, 1952. He gave manysymposia publicly to propagate his ideas. Dummer unsuccessfully attempted to buildsuch a circuit in 1956.

A precursor idea to the IC was to create small ceramic squares (wafers), each

one containing a single miniaturized component. Components could then beintegrated 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 1951's Project Tinkertoy ).[5] 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 akey concept behind the IC. [6]

Jack Kilby 's original integrated circuit

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Jack Kilby recorded his initial ideas concerning the integrated circuit in July1958 and successfully demonstrated the first working integrated circuit on September 12, 1958 In his patent application of February 6, 1959, Kilby described his newdevice as a body of semiconductor material ... wherein all the components of theelectronic circuit are completely integrated Kilby won the 2000 Nobel Prize in

Physics for his part of the invention of the integrated circuit

Robert Noyce also came up with his own idea of an integrated circuit half ayear later than Kilby. Noyce's chip solved many practical problems that Kilby's hadnot. Noyce's chip, made at Fairchild Semiconductor , was made of silicon , whereasKilby's chip was made of germanium .

Generations

In the early days of integrated circuits, only a few transistors could be placedon a chip, as the scale used was large because of the contemporary technology. As thedegree of integration was small, the design was done easily. Later on, millions, andtoday billions, [10] of transistors could be placed on one chip, and to make a gooddesign became a task to be planned thoroughly. This gave rise to new design methods .

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 thetheoretical concept ], from there came the terms for SSI, MSI, VLSI, and ULSI.

SSI circuits were crucial to early aerospace projects, and vice-versa. Both theMinuteman missile and Apollo program needed lightweight digital computers for their inertial guidance systems; the Apollo guidance computer led and motivated theintegrated-circuit technology ,[11] while the Minuteman missile forced it into mass-

production. The Minuteman missile program and various other Navy programsaccounted for the total $4 million integrated circuit market in 1962, and by 1968, U.S.Government space and defense spending still accounted for 37% of the $312 milliontotal production. The demand by the U.S. Government supported the nascent

integrated circuit market until costs fell enough to allow firms to penetrate theindustrial and eventually the consumer markets. The average price per integratedcircuit dropped from $50.00 in 1962 to $2.33 in 1968. [12] Integrated Circuits began toappear in consumer products by 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

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smaller circuit boards, less assembly work (because of fewer separate components),and 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 firstmicroprocessors, that began to be manufactured in moderate quantities in the early1970s, had under 4000 transistors. True LSI circuits, approaching 10000 transistors,

began to be produced around 1974, for computer main memories andsecond-generation microprocessors.

VLSI

Main article: Very-large-scale integration

Upper interconnect layers on an Intel 80486 DX2 microprocessor die.

The final step in the development process, starting in the 1980s and continuingthrough the present, was "very large-scale integration" ( VLSI ). The developmentstarted with hundreds of thousands of transistors in the early 1980s, and continues

beyond several billion transistors as of 2009.

Multiple developments were required to achieve this increased density.Manufacturers moved to smaller rules and cleaner fabs, so that they could make chipswith more transistors and maintain adequate yield. The path of process improvementswas summarized by the International Technology Roadmap for Semiconductors (ITRS). Design tools improved enough to make it practical to finish these designs in areasonable time. The more energy efficient CMOS replaced NMOS and PMOS , avoiding a prohibitive increase in power consumption. Better texts such as thelandmark textbook by Mead and Conway helped schools educate more designers,among other factors.

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In 1986 the first one megabit RAM chips were introduced, which containedmore than one million transistors. Microprocessor chips passed the million transistor mark in 1989 and the billion transistor mark in 2005. The trend continues largelyunabated, with chips introduced in 2007 containing tens of billions of memorytransistors

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 1million transistors.

Wafer-scale integration (WSI) is a system of building very-large integratedcircuits that uses an entire silicon wafer to produce a single "super-chip". Through acombination of large size and reduced packaging, WSI could lead to dramaticallyreduced costs for some systems, notably massively parallel supercomputers. Thename is taken from the term Very-Large-Scale Integration, the current state of the artwhen WSI was being developed.

A system-on-a-chip (SoC or SOC) is an integrated circuit in which all thecomponents needed for a computer or other system are included on a single chip. Thedesign of such a device can be complex and costly, and building disparatecomponents on a single piece of silicon may compromise the efficiency of someelements. However, these drawbacks are offset by lower manufacturing and assembly

costs and by a greatly reduced power budget: because signals among the componentsare 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 asingle circuit. Communication between layers uses on-die signaling, so power consumption is much lower than in equivalent separate circuits. Judicious use of shortvertical wires can substantially reduce overall wire length for faster operation.

Advances in integrated circuits

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 samechip.

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Among the most advanced integrated circuits are the microprocessors or "cores ", which control everything from computers and cellular phones to digitalmicrowave ovens . Digital memory chips and ASICs are examples of other families of integrated circuits that are important to the modern information society . While thecost of designing and developing a complex integrated circuit is quite high, when

spread across typically millions of production units the individual IC cost isminimized. The performance of ICs is high because the small size allows short traceswhich in turn allows low power logic (such as CMOS ) to be used at fast switchingspeeds.

ICs have consistently migrated to smaller feature sizes over the years,allowing more circuitry to be packed on each chip. This increased capacity per unitarea can be used to decrease cost and/or increase functionalitysee Moore's law which, in its modern interpretation, states that the number of transistors in anintegrated circuit doubles every two years. In general, as the feature size shrinks,almost everything improvesthe cost per unit and the switching power consumptiongo down, and the speed goes up. However, ICs with nanometer -scale devices are notwithout their problems, principal among which is leakage current (see subthresholdleakage for a discussion of this), although these problems are not insurmountable andwill 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 isfierce competition among the manufacturers to use finer geometries. This process, andthe expected progress over the next few years, is well described by the InternationalTechnology Roadmap for Semiconductors (ITRS).

In current research projects, integrated circuits are also developed for sensoric applications in medical implants or other bioelectronic devices. Particular sealingstrategies have to be taken in such biogenic environments to avoid corrosion or

biodegradation of the exposed semiconductor materials. As one of the few materialswell established in CMOS technology, titanium nitride TiN turned out asexceptionally stable and well suited for electrode applications in medical implants.

Classification

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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 logicgates , flip-flops , multiplexers , and other circuits in a few square millimeters. Thesmall size of these circuits allows high speed, low power dissipation, and reducedmanufacturing cost compared with board-level integration. These digital ICs,typically microprocessors , DSPs , and micro controllers work using binarymathematics to process "one" and "zero" signals.

Analog ICs, such as sensors, power management circuits , and operationalamplifiers , work by processing continuous signals. They perform functions likeamplification , active filtering , demodulation , mixing , etc. Analog ICs ease the burdenon circuit designers by having expertly designed analog circuits available instead of designing a difficult analog circuit from scratch.

ICs can also combine analog and digital circuits on a single chip to createfunctions such as A/D converters and D/A converters . Such circuits offer smaller size

and lower cost, but must carefully account for signal interference.

ManufacturingFabrication

Main article: Semiconductor fabrication

Rendering of a small standard cell with three metal layers ( dielectric has beenremoved). The sand-colored structures are metal interconnect, with the vertical pillars

being contacts, typically plugs of tungsten. The reddish structures are polysilicongates, and the solid at the bottom is the crystalline silicon bulk.

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Schematic structure of a CMOS chip, as built in the early 2000s. The graphicshows LDD-MISFET's 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 semiconductors of the periodic table of the chemical elements wereidentified as the most likely materials for a solid state vacuum tube . Starting withcopper oxide , proceeding to germanium , then silicon , the materials weresystematically studied in the 1940s and 1950s. Today, silicon monocrystals are themain substrate used for integrated circuits (ICs) although some III-V compounds of the periodic table such as gallium arsenide are used for specialized applications likeLEDs , 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 thesemiconducting 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 special 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, eachdefined by photolithography, and normally shown in different colors. Some layers

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mark where various dopants are diffused into the substrate (called diffusion layers),some define where additional ions are implanted (implant layers), some define theconductors (polysilicon or metal layers), and some define the connections between theconducting layers (via or contact layers). All components are constructed from aspecific combination of these layers.

In a self-aligned CMOS process, a transistor is formed wherever thegate layer (polysilicon or metal) crosses a diffusion layer.

Capacitive structures , in form very much like the parallel conducting plates 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 thelength 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 havememory on the chip. (See the regular array structure at the bottom of the first image.)Although the structures are intricate 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 thevisible spectrum cannot be used to "expose" a layer of material, as they would be toolarge for the features. Thus photons of higher frequencies (typically ultraviolet ) areused to create the patterns for each layer. Because each feature is so small, electronmicroscopes are essential tools for a process engineer who might be debugging afabrication 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 intorectangular 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 arewelded and/or Thermosonic Bonded to pads , usually found around the edge of thedie. After packaging, the devices go through final testing on the same or similar ATEused 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.

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As of 2005, a fabrication facility (commonly known as a semiconductor fab )costs over $1 billion to construct because much of the operation is automated. Themost 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 AMDare 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

Early USSR-made integrated circuit

The earliest integrated circuits were packaged in ceramic flat packs, whichcontinued 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), firstin 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 3050% less than an equivalent DIP, with a typicalthickness that is 70% less. This package has "gull wing" leads protruding from thetwo long sides and a lead spacing of 0.050 inches.

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In the late 1990s, plastic quad flat pack (PQFP) and thin small-outline package (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 arecurrently transitioning from PGA packages on high-end microprocessors to land gridarray (LGA) packages.

Ball grid array (BGA) packages have existed since the 1970s. Flip-chip BallGrid Array packages, which allow for much higher pin count than other packagetypes, 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 issimilar to a printed-circuit board rather than by wires. FCBGA packages allow anarray of input-output signals (called Area-I/O) to be distributed over the entire dierather than being confined to the die periphery.

Traces out of the die, through the package, and into the printed circuit board have very different electrical properties, compared to on-chip signals. They requirespecial design techniques and need much more electric power than signals confined tothe 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, it'scalled an MCM, or Multi-Chip Module . The boundary between a big MCM and asmall printed circuit board is sometimes fuzzy.

Chip labeling and manufacture date

Most integrated circuits large enough to include identifying informationinclude four common sections: the manufacturer's name or logo, the part number, a part production batch number and/or serial number, and a four-digit code thatidentifies when the chip was manufactured. Extremely small surface mounttechnology parts often bear only a number used in a manufacturer's lookup table tofind 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 inweek 41 of 1983, or approximately in October 1983.

Legal protection of semiconductor chip layouts

Main article: Integrated circuit layout design protection

Like most of the other forms of intellectual property, IC layout designs arecreations of the human mind. They are usually the result of an enormous investment,

both in terms of the time of highly qualified experts, and financially. There is acontinuing need for the creation of new layout-designs which reduce the dimensionsof existing integrated circuits and simultaneously increase their functions. The smaller

an integrated circuit, the less the material needed for its manufacture, andthe smaller the space needed to accommodate it. Integrated circuits are utilized in a

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large range of products, including articles of everyday use, such as watches, televisionsets, washing machines, automobiles, etc., as well as sophisticated data processingequipment.

The possibility of copying by photographing each layer of an integrated circuit

and preparing photomasks for its production on the basis of the photographs obtainedis the main reason for the introduction of legislation for the protection of layout-designs.

A diplomatic conference was held at Washington, D.C. , in 1989, whichadopted a Treaty on Intellectual Property in Respect of Integrated Circuits (IPICTreaty). The Treaty on Intellectual Property in respect of Integrated Circuits, alsocalled Washington Treaty or IPIC Treaty (signed at Washington on May 26, 1989) iscurrently not in force, but was partially integrated into the TRIPs agreement.

National laws protecting IC layout designs have been adopted in a number of countries.

Other developments

In the 1980s, programmable integrated circuits were developed. These devicescontain circuits whose logical function and connectivity can be programmed by theuser, rather than being fixed by the integrated circuit manufacturer. This allows asingle chip to be programmed to implement different LSI-type functions such as logicgates , adders and registers . Current devices named FPGAs (Field Programmable GateArrays) can now implement tens of thousands of LSI circuits in parallel and operate

up to 1.5 GHz (Achronix holding the speed record).

The techniques perfected by the integrated circuits industry over the last threedecades have been used to create microscopic machines, known as MEMS . Thesedevices are used in a variety of commercial and military applications. Examplecommercial 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 developedusing CMOS processes. Examples include Intel's DECT cordless phone, or Atheros 's802.11 card.

Future developments seem to follow the multi-core multi-microprocessor paradigm, already used by the Intel and AMD dual-core processors. Intel recentlyunveiled a prototype, "not for commercial sale" chip that bears 80 microprocessors.Each core is capable of handling its own task independently of the others. This is inresponse to the heat-versus-speed limit that is about to be reached using existing

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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.

A piezoelectric sensor is a device that uses the piezoelectric effect to measure pressure , acceleration , strain or force by converting them to an electrical signal.

Applications

Piezoelectric disk used as a guitar pickup

Piezoelectric sensors have proven to be versatile tools for the measurement of various processes. They are used for quality assurance , process control and for research and development in many different industries. Although the piezoelectriceffect was discovered by Curie in 1880, it was only in the 1950s that the piezoelectriceffect started to be used for industrial sensing applications. Since then, this measuring

principle has been increasingly used and can be regarded as a mature technology withan outstanding inherent reliability. It has been successfully used in variousapplications, such as in medical , aerospace , nuclear instrumentation, and as a pressuresensor in the touch pads of mobile phones. In the automotive industry , piezoelectricelements are used to monitor combustion when developing internal combustionengines . The sensors are either directly mounted into additional holes into the cylinder head or the spark/glow plug is equipped with a built in miniature piezoelectric sensor

Piezoelectric sensors have proven to be versatile tools for the measurement of various processes. They are used for quality assurance , process control and for research and development in many different industries. Although the piezoelectriceffect was discovered by Curie in 1880, it was only in the 1950s that the piezoelectriceffect started to be used for industrial sensing applications. Since then, this measuring

principle has been increasingly used and can be regarded as a mature technology withan outstanding inherent reliability. It has been successfully used in variousapplications, such as in medical , aerospace , nuclear instrumentation, and as a pressuresensor in the touch pads of mobile phones. In the automotive industry , piezoelectricelements are used to monitor combustion when developing internal combustionengines . The sensors are either directly mounted into additional holes into the cylinder

head or the spark/glow plug is equipped with a built in miniature piezoelectric sensor

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The rise of piezoelectric technology is directly related to a set of inherent advantages. The high modulus of elasticity of many piezoelectric materials iscomparable to that of many metals and goes up to 10e6 N/m. Even though

piezoelectric sensors are electromechanical systems that react to compression , the sensing elements show almost zero deflection. This is the reason why

piezoelectric sensors are so rugged, have an extremely high natural frequency and anexcellent linearity over a wide amplitude range. Additionally, piezoelectrictechnology is insensitive to electromagnetic fields and radiation , enablingmeasurements under harsh conditions. Some materials used (especially gallium

phosphate [2] or tourmaline ) have an extreme stability even at high temperature,enabling sensors to have a working range of up to 1000C. Tourmaline shows

pyroelectricity in addition to the piezoelectric effect; this is the ability to generate anelectrical signal when the temperature of the crystal changes. This effect is alsocommon to piezoceramic materials.

Principle Strain Sensitivity [V/*] Threshold [*] Span to threshold ratioPiezoelectric 5.0 0.00001 100,000,000Piezoresistive 0.0001 0.0001 2,500,000Inductive 0.001 0.0005 2,000,000Capacitive 0.005 0.0001 750,000

One disadvantage of piezoelectric sensors is that they cannot be used for trulystatic measurements. A static force will result in a fixed amount of charges on the

piezoelectric material. While working with conventional readout electronics,imperfect insulating materials, and reduction in internal sensor resistance will result ina constant loss of electrons , and yield a decreasing signal. Elevated temperaturescause an additional drop in internal resistance and sensitivity. The main effect on the

piezoelectric effect is that with increasing pressure loads and temperature, thesensitivity is reduced due to twin-formation. While quartz sensors need to be cooledduring measurements at temperatures above 300C, special types of crystals likeGaPO4 gallium phosphate do not show any twin formation up to the melting point of the material itself.

However, it is not true that piezoelectric sensors can only be used for very fast processes or at ambient conditions. In fact, there are numerous applications that showquasi-static measurements, while there are other applications with temperatures higher than 500C.

Piezoelectric sensors are also seen in nature. Dry bone is piezoelectric, and isthought by some to act as a biological force sensor.

Principle of operation

Depending on how a piezoelectric material is cut, three main modes of operation can be distinguished: transverse, longitudinal, and shear.

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Transverse effect

A force is applied along a neutral axis (y) and the charges aregenerated along the (x) direction, perpendicular to the line of force. Theamount of charge depends on the geometrical dimensions of the respective

piezoelectric element. When dimensions a ,b,c apply,

C x = d xy F yb / a ,

where a is the dimension in line with the neutral axis, b is in line withthe charge generating axis and d is the corresponding piezoelectric coefficient.

Longitudinal effect

The amount of charge produced is strictly proportional to the appliedforce and is independent of size and shape of the piezoelectric element. Usingseveral elements that are mechanically in series and electrically in parallel isthe only way to increase the charge output. The resulting charge is

C x = d xx F xn,

where d xx is the piezoelectric coefficient for a charge in x-directionreleased by forces applied along x-direction (in pC/ N). F x is the applied Forcein x-direction [N] and n corresponds to the number of stacked elements .

Shear effect

Again, the charges produced are strictly proportional to the appliedforces and are independent of the elements size and shape. For n elementsmechanically in series and electrically in parallel the charge is

C x = 2d xx F xn.

In contrast to the longitudinal and shear effects, the transverse effect opens the possibility to fine-tune sensitivity on the force applied and the element dimension.

Electrical properties

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Schematic symbol and electronic model of a piezoelectric sensor

A piezoelectric transducer has very high DC output impedance and can be

modeled as a proportional voltage source and filter network . The voltage V at thesource is directly proportional to the applied force, pressure, or strain. The outputsignal is then related to this mechanical force as if it had passed through theequivalent circuit.

Frequency response of a piezoelectric sensor; output voltage vs applied force

A detailed model includes the effects of the sensor's mechanical constructionand other non-idealities The inductance Lm is due to the seismic mass and inertia of the sensor itself. C e is inversely proportional to the mechanical elasticity of the sensor.C 0 represents the static capacitance of the transducer, resulting from an inertial massof infinite size. Ri is the insulation leakage resistance of the transducer element. If thesensor is connected to a load resistance , this also acts in parallel with the insulationresistance, both increasing the high-pass cutoff frequency.

In the flat region, the sensor can be modeled as a voltage source in series with

the sensor's capacitance or a charge source in parallel with the capacitance

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For use as a sensor, the flat region of the frequency response plot is typically

used, between the high-pass cutoff and the resonant peak. The load and leakageresistance need to be large enough that low frequencies of interest are not lost. Asimplified equivalent circuit model can be used in this region, in which C s representsthe capacitance of the sensor surface itself, determined by the standard formula for capacitance of parallel plates It can also be modeled as a charge source in parallelwith the source capacitance, with the charge directly proportional to the applied force,as above

Sensor design

Metal disks with piezo material, used in buzzers or as contact microphones

Based on piezoelectric technology various physical quantities can bemeasured; the most common are pressure and acceleration. For pressure sensors, athin membrane and a massive base is used, ensuring that an applied pressurespecifically loads the elements in one direction. For accelerometers , a seismic mass isattached to the crystal elements. When the accelerometer experiences a motion, theinvariant seismic mass loads the elements according to Newtons second law of motion F = ma .

The main difference in the working principle between these two cases is theway forces are applied to the sensing elements. In a pressure sensor a thin membraneis used to transfer the force to the elements, while in accelerometers the forces are

applied by an attached seismic mass.

Sensors often tend to be sensitive to more than one physical quantity. Pressuresensors show false signal when they are exposed to vibrations. Sophisticated pressuresensors therefore use acceleration compensation elements in addition to the pressuresensing elements. By carefully matching those elements, the acceleration signal(released from the compensation element) is subtracted from the combined signal of

pressure and acceleration to derive the true pressure information.

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Vibration sensors can also be used to harvest otherwise wasted energy frommechanical vibrations. This is accomplished by using piezoelectric materials toconvert mechanical strain into usable electrical energy

Sensing materials

Two main groups of materials are used for piezoelectric sensors: piezoelectricceramics and single crystal materials. The ceramic materials (such as PZT ceramic)have a piezoelectric constant / sensitivity that is roughly two orders of magnitude higher than those of single crystal materials and can be produced by inexpensivesintering processes. The piezoeffect in piezoceramics is "trained", so unfortunatelytheir high sensitivity degrades over time. The degradation is highly correlated withtemperature. The less sensitive crystal materials ( gallium phosphate , quartz , tourmaline ) have a much higher when carefully handled, almost infinite long termstability.

How to read Resistor Color CodesFirst the code

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R ed

Orange

Yellow

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