Dictionary Definition
transistor n : a semiconductor device capable of
amplification [syn: junction
transistor, electronic
transistor]
User Contributed Dictionary
English
Pronunciation
-
- Rhymes: -ɪstə(r)
Noun
- a solid-state semiconductor device, with three terminals, which can be used for amplification, switching, voltage stabilization, signal modulation, and many other functions
- In the context of "dated|informal": a transistor radio
Derived terms
Translations
solid-state semiconductor device, with three
terminals
- Czech: tranzistor
small portable radio
- Italian: radiolina
- Dutch: transistor
- French: transistor
- German: Transistor
- Ido: transistoro
- Russian: транзистор (tranzístor)
- Polish: tranzystor
Extensive Definition
In electronics, a transistor is
a semiconductor
device commonly used to amplify
or switch electronic
signals. The transistor is the fundamental building block of
computers, and all
other modern electronic
devices. Some transistors are packaged individually but most
are found in integrated
circuits.
Introduction
An electrical signal can be amplified by using a device that allows a small current or voltage to control the flow of a much larger current. Transistors are the basic devices providing control of this kind. Modern transistors are divided into two main categories: bipolar junction transistors (BJTs) and field effect transistors (FETs). Applying current in BJTs and voltage in FETs between the input and common terminals increases the conductivity between the common and output terminals, thereby controlling current flow between them. The characteristics of a transistor depend on its type.The term "transistor" originally referred to the
point
contact type, which saw very limited commercial application,
being replaced by the much more practical
bipolar junction types in the early 1950s. Today's most widely
used schematic
symbol, like the term "transistor", originally referred to
these long-obsolete devices.
In analog
circuits, transistors are used in amplifiers,
(direct current amplifiers, audio amplifiers, radio frequency
amplifiers), and linear regulated
power supplies. Transistors are also used in digital
circuits where they function as electronic switches, but rarely
as discrete
devices, almost always being incorporated in monolithic
Integrated
Circuits. Digital circuits include logic gates,
random
access memory (RAM), microprocessors, and
digital
signal processors (DSPs).
History
The first patent for the field-effect transistor
principle was filed in Canada by Austrian-Hungarian physicist
Julius
Edgar Lilienfeld on October 22, 1925, but Lilienfeld did not
publish any research articles about his devices, and they were
ignored by industry. In 1934 German physicist Dr. Oskar Heil
patented another field-effect transistor. There is no direct
evidence that these devices were built, but later work in the 1990s
shows that one of Lilienfeld's designs worked as described and gave
substantial gain. Legal papers from the Bell Labs patent show that
Shockley and Pearson had built operational versions from
Lilienfeld's patents, yet they never referenced this work in any of
their later research papers or historical articles.
On 16 December
1947, William
Shockley, John
Bardeen, and Walter
Brattain succeeded in building the first practical point-contact
transistor at Bell Labs. This
work followed from their war-time efforts to produce extremely pure
germanium "crystal"
mixer diodes, used in
radar units as a frequency
mixer element in microwave radar receivers.
They made a demonstration to several of their colleagues and
managers at Bell Labs on the afternoon of 23 December
1947, often
given as the birth date of the transistor. A parallel project on
germanium diodes at Purdue
University succeeded in producing the good-quality germanium
semiconducting crystals that were used at Bell Labs. Early
tube-based technology did not switch fast enough for this role,
leading the Bell team to use solid state diodes instead. With this
knowledge in hand they turned to the design of a triode, but found this was not at
all easy. Bardeen eventually developed a new branch of surface
physics to account for the "odd" behavior they saw, and Bardeen
and Brattain eventually succeeded in building a working
device.
At the same time some European scientists were
led by the idea of solid-state amplifiers. In August 1948 German
physicists Herbert
F. Mataré (1912– ) and Heinrich
Welker (1912–1981), working in Aulnay-sous-Bois,
France, for
Compagnie des Freins et Signaux Westinghouse of Paris, applied for a
patent on an amplifier based on the minority carrier injection
process which they called the "transistron". Since Bell Labs did
not make a public announcement of the transistor until June 1948,
the transistron was considered to be independently developed.
Mataré had first observed transconductance effects during the
manufacture of germanium duodiodes for German radar equipment
during WWII.
Transistrons were commercially manufactured for the French
telephone company and military, and in 1953 a solid-state radio
receiver with four transistrons was demonstrated at the Düsseldorf
Radio Fair.
Bell Telephone Laboratories needed a generic name for the new
invention: "Semiconductor Triode", "Solid Triode", "Surface States
Triode", "Crystal Triode" and "Iotatron" were all considered, but
"transistor," coined by John R.
Pierce, won an internal ballot. The rationale for the name is
described in the following extract from the company's Technical
Memorandum calling for votes:
Pierce recalled the naming somewhat
differently:
Over the next two decades, transistors gradually
replaced the earlier vacuum tubes
in most applications and later made possible many new devices such
as integrated
circuits and personal
computers.
Shockley, Bardeen and Brattain were honored with
the Nobel
Prize in Physics "for their researches on semiconductors and
their discovery of the transistor effect". Bardeen would go on to
win a second Nobel in physics, one of only two people to receive
more than one in the same discipline, for his work on the
exploration of superconductivity.
The commercial uses of germanium transistors were
limited by their sensitivity to temperature and humidity. Silicon,
a semiconductor with crystal structure identical to germanium,
looked promising but attempts over several years to make useful
transistors were unsuccessful. In early 1954, M. Tanenbaum et al.
(Jl. of Applied Physics, 26, 686 (1955)) at Bell Labs made a high
performance silicon transistor using npn junctions produced by
growth rate fluctuations during crystal growing. A few months
later, working independently at Texas Instruments, G. Teal
(unpublished) made similar devices using sequential doping.
While these devices had much superior temperature
and environmental properties compared to gemanium transistors, the
doping processes were difficult to control. That problem was solved
by Tanenbaum and Fuller (Bell Sys. Tech. Jl., 35, 1 (1956)) using
gas diffusion techniques to produce npn silicon transistors. The
resulting diffused base silicon transistor was the subject of the
second Bell Labs symposium. The diffusion process was easy to
control, quickly adopted by the semiconductor industry and was the
basis for the later invention of the integrated circuit initiating
the "silicon age". The first gallium-arsenide Schottky-gate
field-effect transistor (MESFET) was made by
Carver
Mead and reported in 1966.
Importance
The transistor is considered by many to be the greatest invention of the twentieth century. It is the key active component in practically all modern electronics. Its importance in today's society rests on its ability to be mass produced using a highly automated process (fabrication) that achieves astonishingly low per-transistor costs.Although several companies each produce over a
billion individually-packaged (known as discrete)
transistors every year , the vast majority of transistors produced
are in integrated
circuits (often abbreviated as IC and also called microchips or
simply chips) along with diodes, resistors, capacitors and other electronic
components to produce complete electronic circuits. A logic gate
consists of about twenty transistors whereas an advanced
microprocessor, as of 2006, can use as many as 1.7 billion
transistors (MOSFETs).
"About 60 million transistors were built this
year [2002] ... for [each] man, woman, and child on Earth."
The transistor's low cost, flexibility and
reliability have made it a universal device for non-mechanical
tasks, such as digital computing. Transistorized mechatronics circuits have
replaced electromechanical
devices for the control of appliances and machinery as well. It is
often easier and cheaper to use a standard microcontroller and
write a computer
program to carry out a control function than to design an
equivalent mechanical control function.
Because of the low cost of transistors and hence
digital computers, there is a trend to digitize
information, such as the Internet
Archive. With digital computers offering the ability to quickly
find, sort and process digital information, more and
more effort has been put into making information digital. As a
result, today, much media data is delivered in digital form,
finally being converted and presented in analog form to the user.
Areas influenced by the Digital
Revolution include television, radio, and newspapers.
Comparison with vacuum tubes
Prior 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.Advantages
The 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 produced more than 30 years ago are still in service.
- Complementary devices available, facilitating the design of complementary-symmetry circuits, something not possible with vacuum tubes.
- Though in most transistors the junctions have different doping levels and geometry, some allow bidirectional current
- Ability to control very large currents, as much as several hundred amperes.
- Insensitivity to mechanical shock and vibration, thus avoiding the problem of microphonics in audio applications.
- More sensitive than the hot and macroscopic tubes
Disadvantages
- Silicon transistors do not operate at voltages higher than about 1 kV, SiC go to 3 kV.
- The electron mobility is higher in a vacuum, so that high power, high frequency operation is easier in tubes.
Types
|- align = "center" | * Alloy junction transistor- Tetrode transistor
- Pentode transistor
- Spacistor
- Surface barrier transistor
- Micro alloy transistor
- Micro alloy diffused transistor
- Drift-field transistor
- 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 opposite semiconductor type is formed at a point along the length of the body for the third terminal (Emitter).
- Dual gate FETs have a single channel with two gates in cascode; a configuration that is optimized for high frequency amplifiers, mixers, and oscillators.
- 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 on specific 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. Intended for three-phase power supplies, this device houses three NPN IGBTs in a case measuring 38 by 140 by 190 mm and weighing 1.5 kg. Each IGBT is rated at 1,700 volts and can handle 2,400 amperes.
- Single-electron transistors (SET) consist of a gate island between two tunnelling junctions. The tunnelling current is controlled by a voltage applied to the gate through a capacitor. http://www.mitre.org/tech/nanotech/single_electron_transistor.htmlhttp://physicsweb.org/articles/world/11/9/7/1.
- Nanofluidic transistor Control the movement of ions through sub-microscopic, water-filled channels. Nanofluidic transistor, the basis of future chemical processors
- Trigate transistors (Prototype by Intel)
- Avalanche transistor
- Ballistic transistor
- Spin transistor Magnetically-sensitive
- Thin film transistor Used in LCD display.
- Floating-gate transistor Used for non-volatile storage.
- Photo transistor React to light
- Inverted-T field effect transistor
- Ion sensitive field effect transistor To measure ion concentrations in solution.
- FinFET The source/drain region forms fins on the silicon surface.
- FREDFET Fast-Reverse Epitaxial Diode Field-Effect Transistor
- EOSFET Electrolyte-Oxide-Semiconductor Field Effect Transistor (Neurochip)
- OFET Organic Field-Effect Transistor, in which the semiconductor is an organic compound
- DNAFET Deoxyribonucleic acid field-effect transistor
Semiconductor material
The first BJTs were made from germanium (Ge) and some high
power types still are. Silicon (Si) types currently
predominate but certain advanced microwave 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
table below; it must be noted that these parameters will vary with
increase in temperature, electric field, impurity level, strain and
various other factors:
The junction forward voltage is the voltage
applied to the emitter-base junction of a BJT in order to make the
base conduct a specified current. The current increases
exponentially as the junction forward voltage is increased. The
values given in the table are typical for a current of 1 mA (the
same values apply to semiconductor diodes). The lower the junction
forward voltage the better, as this means that less power is
required to "drive" the transistor. The junction forward voltage
for a given current decreases with increase in temperature. For a
typical silicon junction the change is approximately −2.1
mV/°C.
The density of mobile carriers in the channel of
a MOSFET is a function of the electric field forming the channel
and of various other phenomena such as the impurity level in the
channel. Some impurities, called dopants, are introduced
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 the semiconductor material with an electric
field of 1 volt per meter applied across the material. In
general, the higher the electron mobility the faster 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
Max. junction temperature values represent a
cross section taken from various manufacturers' data sheets. This
temperature 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
known as a Schottky
diode. This is included in the table because some silicon power
IGFETs have a parasitic reverse Schottky 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
Transistors come in many different packages
(chip
carriers) (see images). The two main categories are through-hole
(or leaded), and surface-mount, also known as surface mount device
(SMD).
The ball grid array (BGA) is
the latest surface mount package (currently only for large
transistor arrays). It has solder "balls" on the underside in place
of leads. Because they are smaller and have shorter
interconnections, SMDs have better high frequency characteristics
but lower power rating.
Transistor packages are made of glass, metal,
ceramic or plastic. The package often dictates the power rating and
frequency characteristics. Power transistors have large packages
that can be clamped to heat sinks for
enhanced cooling. Additionally, most power transistors have the
collector or drain physically connected to the metal can/metal
plate. At the other extreme, some surface-mount microwave
transistors are as small as grains of sand.
Often a given transistor type is available in
different packages. Transistor packages are mainly standardized,
but the assignment of a transistor's functions to the terminals is
not: different transistor types can assign different functions to
the package's terminals. Even for the same transistor type the
terminal assignment can vary (normally indicated by a suffix letter
to the part number- i.e. BC212L and BC212K).
Usage
For a basic guide to the operation of transistors, see How a transistor works.In the early days of transistor circuit design,
the
bipolar junction transistor, or BJT, was the most commonly used
transistor. Even after MOSFETs became
available, the BJT remained the transistor of choice for digital
and analog circuits because of their ease of manufacture and speed.
However, desirable properties of MOSFETs, such as their utility in
low-power devices, have made them the ubiquitous choice for use in
digital circuits and a very common choice for use in analog
circuits.
Switches
Transistors are commonly used as electronic switches, for both high power applications including switched-mode power supplies and low power applications such as logic gates.Amplifiers
From mobile phones to televisions, vast numbers of products include amplifiers for sound reproduction, radio transmission, and signal processing. The first discrete transistor audio amplifiers barely supplied a few hundred milliwatts, but power and audio fidelity gradually increased as better transistors became available and amplifier architecture evolved.Transistors are commonly used in modern musical
instrument amplifiers, in which circuits up to a few hundred
watts are common and
relatively cheap. Transistors have largely replaced valves (electron
tubes) in instrument amplifiers. Some musical instrument
amplifier manufacturers mix transistors and vacuum tubes in the
same circuit, to utilize the inherent benefits of both
devices.
Computers
The "first generation" of electronic computers used vacuum tubes, which generated large amounts of heat, were bulky, and were unreliable. The development of the transistor was key to computer miniaturization and reliability. The "second generation" of computers, through the late 1950s and 1960s featured boards filled with individual transistors and magnetic memory cores. Subsequently, transistors, other components, and their necessary wiring were integrated into a single, mass-manufactured component: the integrated circuit.See also
References
Further reading
- The invention of the transistor & the birth of the information age
External links
- BBC: Building the digital age photo history of transistors
- Transistor Flow Control — Scientific American Magazine (October 2005)
- The Bell Systems Memorial on Transistors
- IEEE Virtual Museum, Let's Get Small: The Shrinking World of Microelectronics. All about the history of transistors and integrated circuits.
- Transistorized. Historical and technical information from the Public Broadcasting Service
- This Month in Physics History: November 17 to December 23 1947: Invention of the First Transistor. From the American Physical Society
- 50 Years of the Transistor. From Science Friday, December 12 1997
- Bob's Virtual Transistor Museum & History. Treasure trove of transistor history
- Jerry Russell's Transistor Cross Reference Database.
- The DatasheetArchive. Searchable database of transistor specifications and datasheets.
- Charts showing many characteristics and giving direct access to most datasheets for 2N, 2SA, 2SB. 2SC, 2SD, 2SH-K, and other numbers.
Datasheets
A wide range of transistors has been available since the 1960s and manufacturers continually introduce improved types. A few examples from the main families are noted below. Unless otherwise stated, all types are made from silicon semiconductor. Complementary pairs are shown as NPN/PNP or N/P channel. Links go to manufacturer datasheets, which are in PDF format. (On some datasheets the accuracy of the stated transistor category is a matter of debate.)- AF107: Germanium, 0.5 watt, 250 MHz PNP BJT.
- BFP183: Low power, 8 GHz microwave NPN BJT.
- LM394: "supermatch pair", with two NPN BJTs on a single substrate.
- 2SC3281/2SA1302: Made by Toshiba, these BJTs have low-distortion characteristics and are used in high-power audio amplifiers. They have been widely counterfeitedhttp://sound.westhost.com/counterfeit.htm.
- BU508: NPN, 1500 V power BJT. Designed for television horizontal deflection, its high voltage capability also makes it suitable for use in ignition systems.
- MJ11012/MJ11015: 30 A, 120 V, 200 W, high power Darlington complementary pair BJTs. Used in audio amplifiers, control, and power switching.
- BSP296/BSP171: IGFET (enhancement mode), medium power, near complementary pair. Used for logic level conversion and driving power transistors in amplifiers.
Part numbers starting with "2S" are from Japan.
Transistors with part numbers beginning with 2SA or 2SB are PNP
BJTs. Transistors with part numbers beginning with 2SC or 2SD are
NPN BJTs. Transistors with part numbers beginning with 2SJ are
P-channel FETs (both JFETs and MOSFETs). Transistors with part
numbers beginning with 2SK are N-channel FETs (both JFETs and
MOSFETs).
Patents
transistor in Afrikaans: Transistor
transistor in Arabic: ترانزستور
transistor in Bengali: ট্রানজিস্টর
transistor in Belarusian: Транзістар
transistor in Belarusian (Tarashkevitsa):
Транзыстар
transistor in Bosnian: Tranzistor
transistor in Bulgarian: Транзистор
transistor in Catalan: Transistor
transistor in Czech: Tranzistor
transistor in Danish: Transistor
transistor in German: Transistor
transistor in Estonian: Transistor
transistor in Modern Greek (1453-):
Τρανζίστορ
transistor in Spanish: Transistor
transistor in Esperanto: Transistoro
transistor in Basque: Trantsistore
transistor in Persian: ترانزیستور
transistor in French: Transistor
transistor in Friulian: Transistôr
transistor in Galician: Transistor
transistor in Korean: 트랜지스터
transistor in Hindi: ट्रांज़िस्टर
transistor in Croatian: Tranzistor
transistor in Indonesian: Transistor
transistor in Interlingua (International
Auxiliary Language Association): Transistor
transistor in Icelandic: Smári
(rafeindafræði)
transistor in Italian: Transistor
transistor in Hebrew: טרנזיסטור
transistor in Georgian: ტრანზისტორი
transistor in Kazakh: Транзистор
transistor in Latin: Transistrum
transistor in Latvian: Tranzistors
transistor in Hungarian: Tranzisztor
transistor in Mongolian: Транзистор
transistor in Dutch: Transistor
transistor in Japanese: トランジスタ
transistor in Norwegian: Transistor
transistor in Norwegian Nynorsk:
Transistor
transistor in Polish: Tranzystor
transistor in Portuguese: Transístor
transistor in Romanian: Tranzistor
transistor in Russian: Транзистор
transistor in Sicilian: Transìsturi
transistor in Sinhala: ට්රාන්සිස්ටරය
transistor in Simple English: Transistor
transistor in Slovak: Tranzistor
transistor in Slovenian: Tranzistor
transistor in Serbian: Транзистор
transistor in Serbo-Croatian: Tranzistor
transistor in Sundanese: Transistor
transistor in Finnish: Transistori
transistor in Swedish: Transistor
transistor in Tamil: திரிதடையம்
transistor in Tatar: Tranzistor
transistor in Thai: ทรานซิสเตอร์
transistor in Vietnamese: Tranzito
transistor in Turkish: Transistör
transistor in Ukrainian: Транзистор
transistor in Urdu: منتقزاحم
transistor in Yiddish: טראנזיסטאר
transistor in Chinese:
晶体管