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Transistor

Assorted discrete transistors. Packages in order fromtop to bottom: TO-3, TO-126, TO-92, SOT-23

A transistor is a semiconductor device used to amplify and switchelectronic signals. It is made of a solid piece of semiconductormaterial, with at least three terminals for connection to an externalcircuit. A voltage or current applied to one pair of the transistor'sterminals changes the current flowing through another pair ofterminals. Because the controlled (output) power can be muchmore than the controlling (input) power, the transistor providesamplification of a signal. Today, some transistors are packagedindividually, but many more are found embedded in integratedcircuits.

The transistor is the fundamental building block of modernelectronic devices, and is ubiquitous in modern electronic systems.Following its release in the early 1950s the transistorrevolutionized the field of electronics, and paved the way forsmaller and cheaper radios, calculators, and computers, amongother things.

History

A replica of the first working transistor.

Physicist Julius Edgar Lilienfeld filed the first patent for a transistor inCanada in 1925, describing a device similar to a Field Effect Transistoror "FET".[1] However, Lilienfeld did not publish any research articlesabout his devices, nor did his patent cite any examples of devicesactually constructed. In 1934, German inventor Oskar Heil patented asimilar device.[2]

From 1942 Herbert Mataré experimented with so-called duodiodeswhile working on a detector for a Doppler RADAR system. Theduodiodes built by him had two separate but very close metal contactson the semiconductor substrate. He discovered effects that could not beexplained by two independently operating diodes and thus formed thebasic idea for the later point contact transistor.

In 1947, John Bardeen and Walter Brattain at AT&T's Bell Labs in the United States observed that when electricalcontacts were applied to a crystal of germanium, the output power was larger than the input. Solid State PhysicsGroup leader William Shockley saw the potential in this, and over the next few months worked to greatly expand theknowledge of semiconductors. The term transistor was coined by John R. Pierce.[3] According to physicist/historianRobert Arns, legal papers from the Bell Labs patent show that William Shockley and Gerald Pearson had builtoperational versions from Lilienfeld's patents, yet they never referenced this work in any of their later researchpapers or historical articles.[4]

The name transistor is a portmanteau of the term "transfer resistor".[5]

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The first silicon transistor was produced by Texas Instruments in 1954.[6] This was the work of Gordon Teal, anexpert in growing crystals of high purity, who had previously worked at Bell Labs.[7] The first MOS transistoractually built was by Kahng and Atalla at Bell Labs in 1960.[8]

ImportanceThe transistor is the key active component in practically all modern electronics, and is considered by many to be oneof the greatest inventions of the twentieth century.[9] Its importance in today's society rests on its ability to be massproduced using a highly automated process (semiconductor device fabrication) that achieves astonishingly lowper-transistor costs.Although several companies each produce over a billion individually packaged (known as discrete) transistors everyyear,[10] the vast majority of transistors now produced are in integrated circuits (often shortened to IC, microchips orsimply chips), along with diodes, resistors, capacitors and other electronic components, to produce completeelectronic circuits. A logic gate consists of up to about twenty transistors whereas an advanced microprocessor, as of2011, can use as many as 3 billion transistors (MOSFETs).[11] "About 60 million transistors were built this year[2002] ... for [each] man, woman, and child on Earth."[12]

The transistor's low cost, flexibility, and reliability have made it a ubiquitous device. Transistorized mechatroniccircuits have replaced electromechanical devices in controlling appliances and machinery. It is often easier andcheaper to use a standard microcontroller and write a computer program to carry out a control function than to designan equivalent mechanical control function.

UsageThe bipolar junction transistor, or BJT, was the most commonly used transistor in the 1960s and 70s. Even afterMOSFETs became widely available, the BJT remained the transistor of choice for many analog circuits such assimple amplifiers because of their greater linearity and ease of manufacture. Desirable properties of MOSFETs, suchas their utility in low-power devices, usually in the CMOS configuration, allowed them to capture nearly all marketshare for digital circuits; more recently MOSFETs have captured most analog and power applications as well,including modern clocked analog circuits, voltage regulators, amplifiers, power transmitters, motor drivers, etc.

Simplified operation

Simple circuit to show the labels of a bipolar transistor.

The essential usefulness of a transistor comes from its ability touse a small signal applied between one pair of its terminals tocontrol a much larger signal at another pair of terminals. Thisproperty is called gain. A transistor can control its output inproportion to the input signal; that is, it can act as an amplifier.Alternatively, the transistor can be used to turn current on or off ina circuit as an electrically controlled switch, where the amount ofcurrent is determined by other circuit elements.

The two types of transistors have slight differences in how they areused in a circuit. A bipolar transistor has terminals labeled base,collector, and emitter. A small current at the base terminal (thatis, flowing from the base to the emitter) can control or switch amuch larger current between the collector and emitter terminals.For a field-effect transistor, the terminals are labeled gate, source,and drain, and a voltage at the gate can control a current between source and drain.

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The image to the right represents a typical bipolar transistor in a circuit. Charge will flow between emitter andcollector terminals depending on the current in the base. Since internally the base and emitter connections behavelike a semiconductor diode, a voltage drop develops between base and emitter while the base current exists. Theamount of this voltage depends on the material the transistor is made from, and is referred to as VBE.

Transistor as a switch

BJT used as an electronic switch, ingrounded-emitter configuration.

Transistors are commonly used as electronic switches for both high- andlow-power applications such as switched-mode power supplies and logicgates respectively.

In a grounded-emitter transistor circuit, such as the light-switch circuit shown,as the base voltage rises the base and collector current rise exponentially, andthe collector voltage drops because of the collector load resistor. The relevantequations:

VRC = ICE × RC, the voltage across the load (the lamp with resistanceRC)

VRC + VCE = VCC, the supply voltage shown as 6VIf VCE could fall to 0 (perfect closed switch) then Ic could go no higher than VCC / RC, even with higher base voltageand current. The transistor is then said to be saturated. Hence, values of input voltage can be chosen such that theoutput is either completely off,[13] or completely on. The transistor is acting as a switch, and this type of operation iscommon in digital circuits where only "on" and "off" values are relevant.

Transistor as an amplifier

Amplifier circuit, common-emitter configuration.

The common-emitter amplifier is designed so that a small changein voltage in (Vin) changes the small current through the base ofthe transistor and the transistor's current amplification combinedwith the properties of the circuit mean that small swings in Vinproduce large changes in Vout.

Various configurations of single transistor amplifier are possible,with some providing current gain, some voltage gain, and someboth.From mobile phones to televisions, vast numbers of productsinclude amplifiers for sound reproduction, radio transmission, andsignal processing. The first discrete transistor audio amplifiersbarely supplied a few hundred milliwatts, but power and audiofidelity gradually increased as better transistors became availableand amplifier architecture evolved.

Modern transistor audio amplifiers of up to a few hundred watts are common and relatively inexpensive.

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Comparison with vacuum tubesPrior to the development of transistors, vacuum (electron) tubes (or in the UK "thermionic valves" or just "valves")were the main active components in electronic equipment.

AdvantagesThe key advantages that have allowed transistors to replace their vacuum tube predecessors in most applications are• Small size and minimal weight, allowing the development of miniaturized electronic devices.• Highly automated manufacturing processes, resulting in low per-unit cost.• Lower possible operating voltages, making transistors suitable for small, battery-powered applications.• No warm-up period for cathode heaters required after power application.• Lower power dissipation and generally greater energy efficiency.• Higher reliability and greater physical ruggedness.• Extremely long life. Some transistorized devices have been in service for more than 50 years.• Complementary devices available, facilitating the design of complementary-symmetry circuits, something not

possible with vacuum tubes.• Insensitivity to mechanical shock and vibration, thus avoiding the problem of microphonics in audio applications.

Limitations• Silicon transistors do not operate at voltages higher than about 1,000 volts (SiC devices can be operated as high as

3,000 volts). In contrast, vacuum tubes have been developed that can be operated at tens of thousands of volts.• High-power, high-frequency operation, such as that used in over-the-air television broadcasting, is better achieved

in vacuum tubes due to improved electron mobility in a vacuum.• Silicon transistors are much more vulnerable than vacuum tubes to an electromagnetic pulse generated by a

high-altitude nuclear explosion.

Types

PNP P-channel

NPN N-channel

BJT JFET

BJT and JFET symbols

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P-channel

N-channel

JFET MOSFET enh MOSFET dep

JFET and IGFET symbolsTransistors are categorized by• Semiconductor material: germanium, silicon, gallium arsenide, silicon carbide, etc.• Structure: BJT, JFET, IGFET (MOSFET), IGBT, "other types"• Polarity: NPN, PNP (BJTs); N-channel, P-channel (FETs)• Maximum power rating: low, medium, high• Maximum operating frequency: low, medium, high, radio frequency (RF), microwave (The maximum effective

frequency of a transistor is denoted by the term , an abbreviation for "frequency of transition". The frequencyof transition is the frequency at which the transistor yields unity gain).

• Application: switch, general purpose, audio, high voltage, super-beta, matched pair• Physical packaging: through hole metal, through hole plastic, surface mount, ball grid array, power modules• Amplification factor hfe (transistor beta)[14]

Thus, a particular transistor may be described as silicon, surface mount, BJT, NPN, low power, high frequencyswitch.

Bipolar junction transistorBipolar transistors are so named because they conduct by using both majority and minority carriers. The bipolarjunction transistor (BJT), the first type of transistor to be mass-produced, is a combination of two junction diodes,and is formed of either a thin layer of p-type semiconductor sandwiched between two n-type semiconductors (ann-p-n transistor), or a thin layer of n-type semiconductor sandwiched between two p-type semiconductors (a p-n-ptransistor). This construction produces two p-n junctions: a base–emitter junction and a base–collector junction,separated by a thin region of semiconductor known as the base region (two junction diodes wired together withoutsharing an intervening semiconducting region will not make a transistor).The BJT has three terminals, corresponding to the three layers of semiconductor – an emitter, a base, and a collector.It is useful in amplifiers because the currents at the emitter and collector are controllable by a relatively small basecurrent."[15] In an NPN transistor operating in the active region, the emitter-base junction is forward biased(electrons and holes recombine at the junction), and electrons are injected into the base region. Because the base isnarrow, most of these electrons will diffuse into the reverse-biased (electrons and holes are formed at, and moveaway from the junction) base-collector junction and be swept into the collector; perhaps one-hundredth of theelectrons will recombine in the base, which is the dominant mechanism in the base current. By controlling thenumber of electrons that can leave the base, the number of electrons entering the collector can be controlled.[15]

Collector current is approximately β (common-emitter current gain) times the base current. It is typically greater than100 for small-signal transistors but can be smaller in transistors designed for high-power applications.Unlike the FET, the BJT is a low–input-impedance device. Also, as the base–emitter voltage (Vbe) is increased thebase–emitter current and hence the collector–emitter current (Ice) increase exponentially according to the Shockleydiode model and the Ebers-Moll model. Because of this exponential relationship, the BJT has a highertransconductance than the FET.

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Bipolar transistors can be made to conduct by exposure to light, since absorption of photons in the base regiongenerates a photocurrent that acts as a base current; the collector current is approximately β times the photocurrent.Devices designed for this purpose have a transparent window in the package and are called phototransistors.

Field-effect transistorThe field-effect transistor (FET), sometimes called a unipolar transistor, uses either electrons (in N-channel FET) orholes (in P-channel FET) for conduction. The four terminals of the FET are named source, gate, drain, and body(substrate). On most FETs, the body is connected to the source inside the package, and this will be assumed for thefollowing description.In FETs, the drain-to-source current flows via a conducting channel that connects the source region to the drainregion. The conductivity is varied by the electric field that is produced when a voltage is applied between the gateand source terminals; hence the current flowing between the drain and source is controlled by the voltage appliedbetween the gate and source. As the gate–source voltage (Vgs) is increased, the drain–source current (Ids) increasesexponentially for Vgs below threshold, and then at a roughly quadratic rate ( ) (where VT is thethreshold voltage at which drain current begins)[16] in the "space-charge-limited" region above threshold. Aquadratic behavior is not observed in modern devices, for example, at the 65 nm technology node.[17]

For low noise at narrow bandwidth the higher input resistance of the FET is advantageous.FETs are divided into two families: junction FET (JFET) and insulated gate FET (IGFET). The IGFET is morecommonly known as a metal–oxide–semiconductor FET (MOSFET), reflecting its original construction from layersof metal (the gate), oxide (the insulation), and semiconductor. Unlike IGFETs, the JFET gate forms a PN diode withthe channel which lies between the source and drain. Functionally, this makes the N-channel JFET the solid stateequivalent of the vacuum tube triode which, similarly, forms a diode between its grid and cathode. Also, bothdevices operate in the depletion mode, they both have a high input impedance, and they both conduct current underthe control of an input voltage.Metal–semiconductor FETs (MESFETs) are JFETs in which the reverse biased PN junction is replaced by ametal–semiconductor Schottky-junction. These, and the HEMTs (high electron mobility transistors, or HFETs), inwhich a two-dimensional electron gas with very high carrier mobility is used for charge transport, are especiallysuitable for use at very high frequencies (microwave frequencies; several GHz).Unlike bipolar transistors, FETs do not inherently amplify a photocurrent. Nevertheless, there are ways to use them,especially JFETs, as light-sensitive devices, by exploiting the photocurrents in channel–gate or channel–bodyjunctions.FETs are further divided into depletion-mode and enhancement-mode types, depending on whether the channel isturned on or off with zero gate-to-source voltage. For enhancement mode, the channel is off at zero bias, and a gatepotential can "enhance" the conduction. For depletion mode, the channel is on at zero bias, and a gate potential (ofthe opposite polarity) can "deplete" the channel, reducing conduction. For either mode, a more positive gate voltagecorresponds to a higher current for N-channel devices and a lower current for P-channel devices. Nearly all JFETsare depletion-mode as the diode junctions would forward bias and conduct if they were enhancement mode devices;most IGFETs are enhancement-mode types.

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Other transistor types• Point-contact transistor, first kind of transistor ever constructed• Bipolar junction transistor (BJT)

• Heterojunction bipolar transistor, up to several hundred GHz, common in modern ultrafast and RF circuits• Grown-junction transistor, first kind of BJT• Alloy-junction transistor, improvement of grown-junction transistor

• Micro-alloy transistor (MAT), speedier than alloy-junction transistor• Micro-alloy diffused transistor (MADT), speedier than MAT, a diffused-base transistor• Post-alloy diffused transistor (PADT), speedier than MAT, a diffused-base transistor• Schottky transistor• Surface barrier transistor

• Drift-field transistor• Avalanche transistor• Darlington transistors are two BJTs connected together to provide a high current gain equal to the product of

the current gains of the two transistors.• Insulated gate bipolar transistors (IGBTs) use a medium power IGFET, similarly connected to a power BJT, to

give a high input impedance. Power diodes are often connected between certain terminals depending onspecific use. IGBTs are particularly suitable for heavy-duty industrial applications. The Asea Brown Boveri(ABB) 5SNA2400E170100 illustrates just how far power semiconductor technology has advanced.[18] Intendedfor three-phase power supplies, this device houses three NPN IGBTs in a case measuring 38 by 140 by190 mm and weighing 1.5 kg. Each IGBT is rated at 1,700 volts and can handle 2,400 amperes.

• Photo transistor• Field-effect transistor

• Carbon nanotube field-effect transistor (CNFET)• JFET, where the gate is insulated by a reverse-biased PN junction• MESFET, similar to JFET with a Schottky junction instead of PN one

• High Electron Mobility Transistor (HEMT, HFET, MODFET)• MOSFET, where the gate is insulated by a shallow layer of insulator• Inverted-T field effect transistor (ITFET)• FinFET, source/drain region shapes fins on the silicon surface.• FREDFET, fast-reverse epitaxial diode field-effect transistor• Thin film transistor, in LCDs.• OFET Organic Field-Effect Transistor, in which the semiconductor is an organic compound• Ballistic transistor• Floating-gate transistor, for non-volatile storage.• FETs used to sense environment

• Ion sensitive field effect transistor, to measure ion concentrations in solution.• EOSFET, electrolyte-oxide-semiconductor field effect transistor (Neurochip)• DNAFET, deoxyribonucleic acid field-effect transistor

• Spacistor• Diffusion transistor, formed by diffusing dopants into semiconductor substrate; can be both BJT and FET• Unijunction transistors can be used as simple pulse generators. They comprise a main body of either P-type or

N-type semiconductor with ohmic contacts at each end (terminals Base1 and Base2). A junction with the oppositesemiconductor type is formed at a point along the length of the body for the third terminal (Emitter).

• Single-electron transistors (SET) consist of a gate island between two tunnelling junctions. The tunnelling currentis controlled by a voltage applied to the gate through a capacitor.[19]

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• Nanofluidic transistor, controls the movement of ions through sub-microscopic, water-filled channels.Nanofluidic transistor, the basis of future chemical processors [20]

• Multigate devices• Tetrode transistor• Pentode transistor• Multigate device• Trigate transistors (Prototype by Intel)• Dual gate FETs have a single channel with two gates in cascode; a configuration optimized for high frequency

amplifiers, mixers, and oscillators.• Junctionless Nanowire Transistor (JNT), developed at Tyndall National Institute in Ireland, was the first transistor

successfully fabricated without junctions. (Even MOSFETs have junctions, although its gate is electricallyinsulated from the region the gate controls.) Junctions are difficult and expensive to fabricate, and, because theyare a significant source of current leakage, they waste significant power and generate significant waste heat.Eliminating them held the promise of cheaper and denser microchips. The JNT uses a simple nanowire of siliconsurrounded by an electrically isolated "wedding ring" that acts to gate the flow of electrons through the wire. Thismethod has been described as akin to squeezing a garden hose to gate the flow of water through the hose. Thenanowire is heavily n-doped, making it an excellent conductor. Crucially the gate, comprising silicon, is heavilyp-doped; and its presence depletes the underlying silicon nanowire thereby preventing carrier flow past the gate.

Part numbersThe types of some transistors can be parsed from the part number. There are three major semiconductor namingstandards; in each the alphanumeric prefix provides clues to type of the device:Japanese Industrial Standard (JIS) has a standard for transistor part numbers. They begin with "2S",[21] e.g. 2SD965,but sometimes the "2S" prefix is not marked on the package – a 2SD965 might only be marked "D965"; a 2SC1815might be listed by a supplier as simply "C1815". This series sometimes has suffixes (such as "R", "O", "BL"...standing for "Red", "Orange", "Blue" etc.) to denote variants, such as tighter hFE (gain) groupings.

Beginning of Part Number Type of Transistor

2SA high frequency PNP BJTs

2SB audio frequency PNP BJTs

2SC high frequency NPN BJTs

2SD audio frequency NPN BJTs

2SJ P-channel FETs (both JFETs and MOSFETs)

2SK N-channel FETs (both JFETs and MOSFETs)

The Pro Electron part numbers begin with two letters: the first gives the semiconductor type (A for Germanium, Bfor Silicon, and C for materials like GaAs); the second letter denotes the intended use (A for diode, C forgeneral-purpose transistor, etc.). A 3-digit sequence number (or one letter then 2 digits, for industrial types) follows(and, with early devices, indicated the case type – just as the older system for vacuum tubes used the last digit or twoto indicate the number of pins, and the first digit or two for the filament voltage). Suffixes may be used, such as aletter (e.g. "C" often means high hFE, such as in: BC549C[22] ) or other codes may follow to show gain (e.g.BC327-25) or voltage rating (e.g. BUK854-800A[23] ). The more common prefixes are:

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Prefix class Usage Example

AC Germanium small signal transistor AC126

AF Germanium RF transistor AF117

BC Silicon, small signal transistor ("allround") BC548B

BD Silicon, power transistor BD139

BF Silicon, RF (high frequency) BJT or FET BF245

BS Silicon, switching transistor (BJT or MOSFET) BS170

BL Silicon, high frequency, high power (for transmitters) BLW34

BU Silicon, high voltage (for CRT horizontal deflection circuits) BU508

The JEDEC transistor device numbers usually start with 2N, indicating a three-terminal device (dual-gate FieldEffect Transistors are four-terminal devices, so begin with 3N), then a 2, 3 or 4-digit sequential number with nosignificance as to device properties (although low numbers tend to be Germanium devices, because early transistorswere mainly Germanium). For example 2N3055 is a silicon NPN power transistor, 2N1301 is a PNP germaniumswitching transistor. A letter suffix (such as "A") is sometimes used to indicate a newer variant, but rarely gaingroupings.

Other schemes

Manufacturers of devices may have their own proprietary numbering system, for example CK722. Note that amanufacturer's prefix (like "MPF" in MPF102, which originally would denote a Motorola FET) now is an unreliableindicator of who made the device. Some proprietary naming schemes adopt parts of other naming schemes, forexample a PN2222A is a (possibly Fairchild Semiconductor) 2N2222A in a plastic case (but a PN108 is a plasticversion of a BC108, not a 2N108, while the PN100 is unrelated to other xx100 devices).Military part numbers sometimes are assigned their own codes, such as the British Military CV Naming System.Manufacturers buying large numbers of similar parts may have them supplied with "house numbers", identifying aparticular purchasing specification and not necessarily a device with a standardized registered number. For example,an HP part 1854,0053 is a (JEDEC) 2N2218 transistor[24] [25] which is also assigned the CV number: CV7763[26]

Naming problems

With so many independent naming schemes, and the abbreviation of part numbers when printed on the devices,ambiguity sometimes occurs. For example two different devices may be marked "J176" (one the J176 low-powerJunction FET, the other the higher-powered MOSFET 2SJ176).As older "through-hole" transistors are given Surface-Mount packaged counterparts, they tend to be assigned manydifferent part numbers because manufacturers have their own systems to cope with the variety in pinoutarrangements and options for dual or matched NPN+PNP devices in one pack. So even when the original device(such as a 2N3904) may have been assigned by a standards authority, and well known by engineers over the years,the new versions are far from standardised in their naming.

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Construction

Semiconductor materialThe first BJTs were made from germanium (Ge). Silicon (Si) types currently predominate but certain advancedmicrowave and high performance versions now employ the compound semiconductor material gallium arsenide(GaAs) and the semiconductor alloy silicon germanium (SiGe). Single element semiconductor material (Ge and Si)is described as elemental.Rough parameters for the most common semiconductor materials used to make transistors are given in the tablebelow; it must be noted that these parameters will vary with increase in temperature, electric field, impurity level,strain, and sundry other factors:

Semiconductor material characteristics

Semiconductormaterial

Junctionforwardvoltage

V @ 25 °C

Electronmobility

m2/(V·s) @ 25 °C

Hole mobilitym2/(V·s) @ 25 °C

Max. junctiontemp.

°C

Ge 0.27 0.39 0.19 70 to 100

Si 0.71 0.14 0.05 150 to 200

GaAs 1.03 0.85 0.05 150 to 200

Al-Si junction 0.3 — — 150 to 200

The junction forward voltage is the voltage applied to the emitter-base junction of a BJT in order to make the baseconduct a specified current. The current increases exponentially as the junction forward voltage is increased. Thevalues given in the table are typical for a current of 1 mA (the same values apply to semiconductor diodes). Thelower the junction forward voltage the better, as this means that less power is required to "drive" the transistor. Thejunction forward voltage for a given current decreases with increase in temperature. For a typical silicon junction thechange is −2.1 mV/°C.[27] In some circuits special compensating elements (sensistors) must be used to compensatefor such changes.The density of mobile carriers in the channel of a MOSFET is a function of the electric field forming the channel andof various other phenomena such as the impurity level in the channel. Some impurities, called dopants, areintroduced deliberately in making a MOSFET, to control the MOSFET electrical behavior.The electron mobility and hole mobility columns show the average speed that electrons and holes diffuse through thesemiconductor material with an electric field of 1 volt per meter applied across the material. In general, the higherthe electron mobility the speedier the transistor. The table indicates that Ge is a better material than Si in this respect.However, Ge has four major shortcomings compared to silicon and gallium arsenide:• Its maximum temperature is limited;• it has relatively high leakage current;• it cannot withstand high voltages;• it is less suitable for fabricating integrated circuits.Because the electron mobility is higher than the hole mobility for all semiconductor materials, a given bipolar NPNtransistor tends to be swifter than an equivalent PNP transistor type. GaAs has the highest electron mobility of thethree semiconductors. It is for this reason that GaAs is used in high frequency applications. A relatively recent FETdevelopment, the high electron mobility transistor (HEMT), has a heterostructure (junction between differentsemiconductor materials) of aluminium gallium arsenide (AlGaAs)-gallium arsenide (GaAs) which has twice theelectron mobility of a GaAs-metal barrier junction. Because of their high speed and low noise, HEMTs are used insatellite receivers working at frequencies around 12 GHz.

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Max. junction temperature values represent a cross section taken from various manufacturers' data sheets. Thistemperature should not be exceeded or the transistor may be damaged.Al–Si junction refers to the high-speed (aluminum–silicon) semiconductor–metal barrier diode, commonly knownas a Schottky diode. This is included in the table because some silicon power IGFETs have a parasitic reverseSchottky diode formed between the source and drain as part of the fabrication process. This diode can be a nuisance,but sometimes it is used in the circuit.

Packaging

Through-hole transistors (tape measure marked in centimetres)

Transistors come in many different packages(semiconductor packages) (see images). The two maincategories are through-hole (or leaded), andsurface-mount, also known as surface mount device(SMD). The ball grid array (BGA) is the latest surfacemount package (currently only for large transistorarrays). It has solder "balls" on the underside in placeof leads. Because they are smaller and have shorterinterconnections, SMDs have better high frequencycharacteristics but lower power rating.

Transistor packages are made of glass, metal, ceramic, or plastic. The package often dictates the power rating andfrequency characteristics. Power transistors have larger packages that can be clamped to heat sinks for enhancedcooling. Additionally, most power transistors have the collector or drain physically connected to the metal can/metalplate. At the other extreme, some surface-mount microwave transistors are as small as grains of sand.

Often a given transistor type is available in sundry packages. Transistor packages are mainly standardized, but theassignment of a transistor's functions to the terminals is not: other transistor types can assign other functions to thepackage's terminals. Even for the same transistor type the terminal assignment can vary (normally indicated by asuffix letter to the part number, q.e. BC212L and BC212K).

References[1] Lilienfeld, Julius Edgar, "Method and apparatus for controlling electric current" U.S. Patent 1745175 (http:/ / www. google. com/

patents?vid=1745175) 1930-01-28 (filed in Canada 1925-10-22, in US 1926-10-08).[2] Heil, Oskar, "Improvements in or relating to electrical amplifiers and other control arrangements and devices" (http:/ / v3. espacenet. com/

publicationDetails/ biblio?CC=GB& NR=439457& KC=& FT=E), Patent No. GB439457, European Patent Office, filed in Great Britain1934-03-02, published 1935-12-06 (originally filed in Germany 1934-03-02).

[3] David Bodanis (2005). Electric Universe. Crown Publishers, New York. ISBN 0-7394-5670-9.[4] Arns, Robert G. (October 1998). "The other transistor: early history of the metal-oxide-semiconductor field-effect transistor" (http:/ /

ieeexplore. ieee. org/ xpls/ abs_all. jsp?arnumber=730824). Engineering Science and Education Journal 7 (5): 233–240.doi:10.1049/esej:19980509. ISSN 0963-7346. .

[5] "transistor". American Heritage Dictionary (3rd ed.). Boston: Houghton Mifflin. 1992.[6] J. Chelikowski, "Introduction: Silicon in all its Forms", Silicon: evolution and future of a technology (Editors: P. Siffert, E. F. Krimmel), p.1,

Springer, 2004 ISBN 3-540-40546-1.[7] Grant McFarland, Microprocessor design: a practical guide from design planning to manufacturing, p.10, McGraw-Hill Professional, 2006

ISBN 0-07-145951-0.[8] W. Heywang, K. H. Zaininger, "Silicon: The Semiconductor Material", Silicon: evolution and future of a technology (Editors: P. Siffert, E. F.

Krimmel), p.36, Springer, 2004 ISBN 3-540-40546-1.[9] Robert W. Price (2004). Roadmap to Entrepreneurial Success (http:/ / books. google. com/ ?id=q7UzNoWdGAkC& pg=PA42&

dq=transistor+ inventions-of-the-twentieth-century). AMACOM Div American Mgmt Assn. p. 42. ISBN 9780814471906. .[10] FETs/MOSFETs: Smaller apps push up surface-mount supply (http:/ / www. globalsources. com/ gsol/ I/ FET-MOSFET/ a/

9000000085806. htm)[11] " ATI and Nvidia face off (http:/ / news. cnet. com/ 8301-13512_3-10369441-23. html)." Oct 7, 2009. Retrieved on Feb 2, 2011.

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[12] Turley, J. (December 18, 2002). The Two Percent Solution (http:/ / www. embedded. com/ shared/ printableArticle.jhtml?articleID=9900861). Embedded.com.

[13] apart from a small value due to leakage currents[14] "Transistor Example" (http:/ / www. bcae1. com/ transres. htm). . 071003 bcae1.com[15] Streetman, Ben (1992). Solid State Electronic Devices. Englewood Cliffs, NJ: Prentice-Hall. pp. 301–305. ISBN 0-13-822023-9.[16] Horowitz, Paul; Winfield Hill (1989). The Art of Electronics (2nd ed.). Cambridge University Press. pp. 115. ISBN 0-521-37095-7.[17] W. M. C. Sansen (2006). Analog design essentials (http:/ / worldcat. org/ isbn/ 0387257462). New York ; Berlin: Springer. p. §0152, p. 28.

ISBN 0-387-25746-2. .[18] IGBT Module 5SNA 2400E170100 (http:/ / library. abb. com/ GLOBAL/ SCOT/ scot256. nsf/ VerityDisplay/

E700072B04381DD9C12571FF002D2CFE/ $File/ 5SNA 2400E170100_5SYA1555-03Oct 06. pdf)[19] Single Electron Transistors (http:/ / snow. stanford. edu/ ~shimbo/ set. html)[20] http:/ / www. berkeley. edu/ news/ media/ releases/ 2005/ 06/ 28_transistor. shtml[21] Clive TEC Transistors Japanese Industrial Standards (http:/ / www. clivetec. 0catch. com/ Transistors. htm#JIS)[22] http:/ / www. fairchildsemi. com/ ds/ BC/ BC549. pdf Datasheet for BC549, with A,B and C gain groupings[23] http:/ / www. datasheetcatalog. org/ datasheet/ philips/ BUK854-800A. pdf datasheet for BUK854-800A (800volt IGBT)[24] http:/ / www. hpmuseum. org/ cgi-sys/ cgiwrap/ hpmuseum/ archv010. cgi?read=27258 Richard Freeman's HP Part numbers Crossreference[25] http:/ / www. arrl. org/ qexfiles/ 300-hpxref. pdf ARRL Transistor–Diode Cross Reference – H.P. Part Numbers to JEDEC (pdf)[26] http:/ / www. qsl. net/ g8yoa/ cv_table. html CV Device Cross-reference by Andy Lake[27] A.S. Sedra and K.C. Smith (2004). Microelectronic circuits (Fifth ed.). New York: Oxford University Press. pp. 397 and Figure 5.17.

ISBN 0-19-514251-9.

Further reading• Amos S W & James M R (1999). Principles of Transistor Circuits. Butterworth-Heinemann.

ISBN 0-7506-4427-3.• Bacon, W. Stevenson (1968). "The Transistor's 20th Anniversary: How Germanium And A Bit of Wire Changed

The World" (http:/ / books. google. com/ ?id=mykDAAAAMBAJ& printsec=frontcover). Bonnier Corp.:Popular Science, retrieved from Google Books 2009-03-22 (Bonnier Corporation) 192 (6): 80–84.ISSN 0161-7370.

• Horowitz, Paul & Hill, Winfield (1989). The Art of Electronics. Cambridge University Press.ISBN 0-521-37095-7.

• Riordan, Michael & Hoddeson, Lillian (1998). Crystal Fire. W.W Norton & Company Limited.ISBN 0-393-31851-6. The invention of the transistor & the birth of the information age

• Warnes, Lionel (1998). Analogue and Digital Electronics. Macmillan Press Ltd. ISBN 0-333-65820-5.• "Herbert F. Mataré, An Inventor of the Transistor has his moment" (http:/ / www. mindfully. org/ Technology/

2003/ Transistor-Matare-Inventor24feb03. htm). The New York Times. 24 February 2003.• Michael Riordan (2005). "How Europe Missed the Transistor" (http:/ / spectrum. ieee. org/ print/ 2155). IEEE

Spectrum 42 (11): 52–57. doi:10.1109/MSPEC.2005.1526906.• C. D. Renmore (1980). Silicon Chips and You.• Wiley-IEEE Press. Complete Guide to Semiconductor Devices, 2nd Edition.

External links• The Transistor (http:/ / nobelprize. org/ educational_games/ physics/ transistor/ function/ index. html) Educational

content from Nobelprize.org• BBC: Building the digital age (http:/ / news. bbc. co. uk/ 2/ hi/ technology/ 7091190. stm) photo history of

transistors• Transistor Flow Control (http:/ / www. sciam. com/ article. cfm?chanID=sa004&

articleID=000D5D9F-A849-1330-A54583414B7F0000) — Scientific American Magazine (October 2005)• The Bell Systems Memorial on Transistors (http:/ / www. porticus. org/ bell/ belllabs_transistor. html)• IEEE Global History Network, The Transistor and Portable Electronics (http:/ / www. ieeeghn. org/ wiki/ index.

php/ The_Transistor_and_Portable_Electronics). All about the history of transistors and integrated circuits.

Transistor 13

• Transistorized (http:/ / www. pbs. org/ transistor/ ). Historical and technical information from the PublicBroadcasting Service

• This Month in Physics History: November 17 to December 23, 1947: Invention of the First Transistor (http:/ /www. aps. org/ publications/ apsnews/ 200011/ history. cfm). From the American Physical Society

• 50 Years of the Transistor (http:/ / www. sciencefriday. com/ pages/ 1997/ Dec/ hour1_121297. html). FromScience Friday, December 12, 1997

• Bob's Virtual Transistor Museum & History (http:/ / users. arczip. com/ rmcgarra2/ index. html). Treasure troveof transistor history

• Jerry Russell's Transistor Cross Reference Database (http:/ / www. ee. washington. edu/ circuit_archive/ parts/cross. html).

• The DatasheetArchive (http:/ / www. datasheetarchive. com/ ). Searchable database of transistor specificationsand datasheets.

• Charts showing many characteristics and giving direct access to most datasheets for 2N (http:/ / www. classiccmp.org/ rtellason/ transistors-2n. html), 2SA (http:/ / www. classiccmp. org/ rtellason/ transistors-2sa. html), 2SB(http:/ / www. classiccmp. org/ rtellason/ transistors-2sb. html). 2SC (http:/ / www. classiccmp. org/ rtellason/transistors-2sc. html), 2SD (http:/ / www. classiccmp. org/ rtellason/ transistors-2sd. html), 2SH-K (http:/ / www.classiccmp. org/ rtellason/ transistors-2sh-k. html), and other (http:/ / www. classiccmp. org/ rtellason/transistors-3up. html) numbers.

• http:/ / userpages. wittenberg. edu/ bshelburne/ Comp150/ LogicGatesCircuits. html• A short video showing how a transistor works (http:/ / www. vega. org. uk/ video/ programme/ 222).

DatasheetsA wide range of transistors has been available since the 1960s and manufacturers continually introduce improvedtypes. A few examples from the main families are noted below. Unless otherwise stated, all types are made fromsilicon semiconductor. Complementary pairs are shown as NPN/PNP or N/P channel. Links go to manufacturerdatasheets, which are in PDF format. (On some datasheets the accuracy of the stated transistor category is a matter ofdebate.)• 2N3904 (http:/ / www. onsemi. com/ pub/ Collateral/ 2N3903-D. PDF)/ 2N3906 (http:/ / www. onsemi. com/ pub/

Collateral/ 2N3906-D. PDF), BC182 (http:/ / www. onsemi. com/ pub/ Collateral/ BC182-D. PDF)/ BC212 (http:// www. onsemi. com/ pub/ Collateral/ BC212-D. PDF) and BC546 (http:/ / www. onsemi. com/ pub/ Collateral/BC546-D. PDF)/ BC556 (http:/ / www. onsemi. com/ pub/ Collateral/ BC556B-D. PDF): Ubiquitous, BJT,general-purpose, low-power, complementary pairs. They have plastic cases and cost roughly ten cents US in smallquantities, making them popular with hobbyists.

• AF107: Germanium, 0.5-watt, 250 MHz PNP BJT.• BFP183: Low power, 8 GHz microwave NPN BJT.• LM394 (http:/ / www. national. com/ ds/ LM/ LM194. pdf): "supermatch pair", with two NPN BJTs on a single

substrate.• 2N2219A (http:/ / www. st. com/ stonline/ books/ pdf/ docs/ 9288. pdf)/ 2N2905A (http:/ / www. st. com/

stonline/ books/ pdf/ docs/ 9037. pdf): BJT, general purpose, medium power, complementary pair. With metalcases they are rated at about one watt.

• 2N3055 (http:/ / www. onsemi. com/ pub/ Collateral/ 2N3055-D. PDF)/ MJ2955 (http:/ / www. onsemi. com/pub/ Collateral/ 2N3055-D. PDF): For years, the venerable NPN 2N3055 has been the "standard" powertransistor. Its complement, the PNP MJ2955 arrived later. These 1 MHz, 15A, 60V, 115W BJTs are used in audiopower amplifiers, power supplies, and control.

• 2N7000 is a typical small-signal field-effect transistor.• 2SC3281/2SA1302: Made by Toshiba, these BJTs have low-distortion characteristics and are used in high-power

audio amplifiers. They have been widely counterfeited (http:/ / sound. westhost. com/ counterfeit. htm).

Transistor 14

• BU508 (http:/ / www. st. com/ stonline/ books/ pdf/ docs/ 4491. pdf): NPN, 1500 V power BJT. Designed fortelevision horizontal deflection, its high voltage capability also makes it suitable for use in ignition systems.

• MJ11012/MJ11015 (http:/ / www. onsemi. com/ pub/ Collateral/ MJ11012-D. PDF): 30 A, 120 V, 200 W, highpower Darlington complementary pair BJTs. Used in audio amplifiers, control, and power switching.

• 2N5457 (http:/ / www. fairchildsemi. com/ ds/ 2N/ 2N5457. pdf)/ 2N5460 (http:/ / www. fairchildsemi. com/ ds/2N/ 2N5460. pdf): JFET (depletion mode), general purpose, low power, complementary pair.

• BSP296/BSP171: IGFET (enhancement mode), medium power, near complementary pair. Used for logic levelconversion and driving power transistors in amplifiers.

• IRF3710 (http:/ / www. irf. com/ product-info/ datasheets/ data/ irf3710. pdf)/ IRF5210 (http:/ / www. irf. com/product-info/ datasheets/ data/ irf5210. pdf): IGFET (enhancement mode), 40A, 100V, 200W, nearcomplementary pair. For high-power amplifiers and power switches, especially in automobiles.

Patents• US 1745175 (http:/ / v3. espacenet. com/ textdoc?DB=EPODOC& IDX=US1745175) Julius Edgar Lilienfeld:

"Method and apparatus for controlling electric current" first filed in Canada on 22.10.1925, describing a devicesimilar to a MESFET

• US 1900018 (http:/ / v3. espacenet. com/ textdoc?DB=EPODOC& IDX=US1900018) Julius Edgar Lilienfeld:"Device for controlling electric current" filed on 28.03.1928, a thin film MOSFET

• GB 439457 (http:/ / v3. espacenet. com/ textdoc?DB=EPODOC& IDX=GB439457) Oskar Heil: "Improvementsin or relating to electrical amplifiers and other control arrangements and devices" first filed in Germany on02.03.1934

• US 2524035 (http:/ / v3. espacenet. com/ textdoc?DB=EPODOC& IDX=US2524035) J. Bardeen et al.:"Three-electrode circuit element utilizing semiconductive materials" oldest priority 26.02.1948

• US 2569347 (http:/ / v3. espacenet. com/ textdoc?DB=EPODOC& IDX=US2569347) W. Shockley: "Circuitelement utilizing semiconductive material" oldest priority 26.06.1948

Article Sources and Contributors 15

Article Sources and ContributorsTransistor  Source: http://en.wikipedia.org/w/index.php?oldid=414628765  Contributors: 07mahmooda, 144.132.70.xxx, 213.253.39.xxx, 216.237.32.xxx, 2n3055, 6pence, 84user, @modi, A. diM., ABF, AG SILVER92, AJR, Acroterion, Aeons, Ahoerstemeier, Ahseaton, Aitias, Akjahid, Alan Liefting, Alansohn, Ale2006, Alf loves chocolate, Allstarecho, Alvin-cs, Ancheta Wis, AndyM. Wang, Anirak1337, Antandrus, Apsrobillo, Area51david, Arnero, ArnoldReinhold, Asher196, Ashley Pomeroy, Atlant, Attilios, Avihu, Avin, Axonn77, BWDuncan, Babbage, Bar0n,Barfooz, Barium, Beatnik8983, Begemotv2718, Bernard van der Wees, BigChicken, Bigdumbdinosaur, Bkell, Blanchardb, Bleh999, Blobglob, Bloodshedder, Bludude90210, Bobo192,Bogdangiusca, Bongwarrior, Boots232, Brejc8, Brews ohare, Brian Kendig, Brinkost, Britcom, Bubbachuck, Bucko1992, C0nanPayne, COMPATT, CPES, Caiaffa, Cal 1234, Cameronled, Can'tsleep, clown will eat me, CanOfWorms, CanadianLinuxUser, CanisRufus, Capitalistroadster, Capricorn42, Captain Quirk, Captain-tucker, Carl086, Carlsotr, Casper2k3, Cbdorsett, CboneG5,Cburnett, Cc2po, Charlvn, Chcknwnm, Chetvorno, Chinneeb, Chmyr, Chowbok, ChrisfromHouston, Chrismon, Chrumps, Circuitsmith, Closedmouth, Cmcginnis, Cocytus, CodyARay, ColinHill, Commissar Mo, Compnerd09, Compy 386, Coneslayer, Conical Johnson, Conversion script, Cornellrockey, CosineKitty, Cprompt, Crispmuncher, Cronostvg, Cyan, Cyp, CyrilB, DJLoPaTa, DMacks, DV8 2XL, DVdm, Dadude3320, Dagnabit, Dan D. Ric, DanB, Danorux, DarkCell, Darth Mike, DatasheetArchive, Davehi1, David Carron, David Gerard, DavideAndrea,Davidperson, Dcandeto, DeadEyeArrow, Dekisugi, Delldot, Denimadept, Der Falke, Dfeuer, Dfries, Dicklyon, Discospinster, Dman223, Dmeranda, Dmillard10, DonSiano, Dooley3956, Dorit82,Dovo, Dpbsmith, Dratman, Dricherby, Dwandelt, Dyl, EEPROM Eagle, EarthPerson, Editor at Large, Efa, El C, Electron9, Elekas, Elipongo, Elliskev, Ellmist, Em3ryguy, Emc2, EncMstr,Enochlau, Enviroboy, Epbr123, Eric Kvaalen, EricBarbour, Ericoides, Esolbiz, Explicit, FDominec, Faranak moradipoor, Farosdaughter, Favonian, Ferkelparade, Fieldday-sunday, Firespray,Firq, Fleminra, Flewis, Flockmeal, Flying fish, Foogod, Forrest575757, Fraggle81, Frankenpuppy, Fredrik, Freetall, G-W, GAMER 20999, GW Simulations, Gadfium, Gaius Cornelius,Galexander, Galootius, Garyzx, Gbraad, Gene Nygaard, Geniusinfranceman, George The Dragon, Gerry Ashton, Giftlite, Gilliam, Gjd001, Glane23, Glenn, Gparker, Graham87, Grendelkhan,Guillermo90r, Gurch, Habibi 66, Hadal, Haham hanuka, Haikupoet, Hairy Dude, Hammack, Harryzilber, HeKeRnd, Headbomb, Hellcat fighter, HenryLi, Heron, Hhcox, Hmsbeagle, HodgeBrad,HolIgor, Hooperbloob, Hébus, I80and, IFly, Iammaxus, IanOfNorwich, Ilikefood, Imchandan, Immunize, Interiot, Iridescent, IronGargoyle, Ixfd64, J.delanoy, JSimmonz, JVz, Jackelfive, Jakohn,Jamesontai, Jared81, Jayzor123, Jc3s5h, Jeh, Jessemonroy650, Jiang, Jidan, Jimaginator, Jimmi Hugh, Jimp, Jindrich, Jklin, Jkominek, Jleedev, JohnCD, JohnOwens, Jojit fb, Jomasecu, JonS117,JonathanFreed, Jondel, Jonnic1, Jossi, Jovianconflict, Jpbowen, Julesd, KJS77, Kaeslin, Katieh5584, Kbh3rd, Kevin aylward, Kient123, King Lopez, Kirachinmoku, Kjkolb, Klenje, KnowledgeSeeker, Kostisl, Krishnavedala, Kungfuadam, Kurdestan, Kuru, L Kensington, Lankiveil, Lantrix, Larry_Sanger, Lazylaces, Ldo, LeAwesome0001, LeaveSleaves, LedgendGamer, Leon7, Lightcurrent, Lightmouse, Ligulem, Lindosland, Lissajous, Little guru, LiuyuanChen, LjL, Lommer, Loren.wilton, Luna Santin, MER-C, MIT Trekkie, MONGO, Magister Mathematicae, Maheshkale,Mahya42, Maitchy, Mako098765, Malleus Fatuorum, Mani1, Marginoferror, MarkSutton, Markk01, Marshman, Masoud691, Master Jay, Masterpiece2000, Mat-C, Materialscientist, Matijap,Matt B., Matt Britt, Mattgirling, Maury Markowitz, Mav, Maximus Rex, Mentisock, Mermadak, Mets501, Michael Hardy, MichaelBillington, MigueldelosSantos, Mike Dill, Mike Rosoft,Mike1975, Mikel Ward, Mikespedia, Mild Bill Hiccup, Mindspillage, Minnesota1, Misza13, Mjm1964, ModernGeek, Mr snarf, MrOllie, Msiddalingaiah, Mudlock, Nakon, Natalie Erin,NawlinWiki, Nazli, Nedim Ardoğa, NeilUK, Nezzadar, Nihiltres, Nikai, Ninly, Nixdorf, Noctibus, Nokkosukko, NorthernNerd, Northfox, Nsaa, ONEder Boy, Oda Mari, Omegatron, Oneliner,OregonD00d, OrgasGirl, Orimosenzon, Pakaraki, Palica, Papa November, Pcu123456789, PeterGrecian, Phil Boswell, PhilKnight, Philip Trueman, Pigsonthewing, Pinethicket, Pjacobi, Pjedicke,Plugwash, Plutor, Pmronchi, Poindexter Propellerhead, Polyparadigm, Prari, Privatise, Profurp, Puchiko, Pyfan, Pyrosim, QEDquid, Qdr, Quantumsilverfish, R. 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Image Sources, Licenses and ContributorsImage:Transistorer (croped).jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Transistorer_(croped).jpg  License: GNU Free Documentation License  Contributors: Transisto aten.wikipediaImage:Replica-of-first-transistor.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Replica-of-first-transistor.jpg  License: Public Domain  Contributors: Daderot, Glenn, Hdelacy,Mnd, Nagy, Para, Ragesoss, Topory, WikipediaMaster, 3 anonymous editsImage:Transistor2.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Transistor2.svg  License: Free Art License  Contributors: User:@modi, User:CatKiller, User:rodhullandemuImage:Transistor as switch.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Transistor_as_switch.svg  License: Public Domain  Contributors: FDominecFile:Common emitter.png  Source: http://en.wikipedia.org/w/index.php?title=File:Common_emitter.png  License: unknown  Contributors: Bukk, FDominec, Inductiveload, Omegatron, Paddy,Yves-Laurent, ZedhImage:BJT PNP symbol.svg  Source: http://en.wikipedia.org/w/index.php?title=File:BJT_PNP_symbol.svg  License: unknown  Contributors: User:OmegatronImage:JFET P-Channel Labelled.svg  Source: http://en.wikipedia.org/w/index.php?title=File:JFET_P-Channel_Labelled.svg  License: Public Domain  Contributors: jjbeardImage:BJT NPN symbol.svg  Source: http://en.wikipedia.org/w/index.php?title=File:BJT_NPN_symbol.svg  License: unknown  Contributors: User:OmegatronImage:JFET N-Channel Labelled.svg  Source: http://en.wikipedia.org/w/index.php?title=File:JFET_N-Channel_Labelled.svg  License: Public Domain  Contributors: jjbeardImage:IGFET P-Ch Enh Labelled.svg  Source: http://en.wikipedia.org/w/index.php?title=File:IGFET_P-Ch_Enh_Labelled.svg  License: Public Domain  Contributors: jjbeardImage:IGFET P-Ch Enh Labelled simplified.svg  Source: http://en.wikipedia.org/w/index.php?title=File:IGFET_P-Ch_Enh_Labelled_simplified.svg  License: unknown  Contributors:User:OmegatronImage:IGFET P-Ch Dep Labelled.svg  Source: http://en.wikipedia.org/w/index.php?title=File:IGFET_P-Ch_Dep_Labelled.svg  License: Public Domain  Contributors: jjbeardImage:IGFET N-Ch Enh Labelled.svg  Source: http://en.wikipedia.org/w/index.php?title=File:IGFET_N-Ch_Enh_Labelled.svg  License: Public Domain  Contributors: Cepheiden, Deadstar,Jjbeard, Zedh, 4 anonymous editsImage:IGFET N-Ch Enh Labelled simplified.svg  Source: http://en.wikipedia.org/w/index.php?title=File:IGFET_N-Ch_Enh_Labelled_simplified.svg  License: unknown  Contributors:User:OmegatronImage:IGFET N-Ch Dep Labelled.svg  Source: http://en.wikipedia.org/w/index.php?title=File:IGFET_N-Ch_Dep_Labelled.svg  License: Public Domain  Contributors: jjbeardImage:Transistor-photo.JPG  Source: http://en.wikipedia.org/w/index.php?title=File:Transistor-photo.JPG  License: GNU Free Documentation License  Contributors: AKA MBG, BethOHara,EugeneZelenko, Glenn, Paddy, Severino666

LicenseCreative Commons Attribution-Share Alike 3.0 Unportedhttp:/ / creativecommons. org/ licenses/ by-sa/ 3. 0/