Electronic devices have significantly influenced the development of many aspects of modern society, such astelecommunications, entertainment, education, health care, industry, and security. The main driving force behind the advancement of electronics is thesemiconductor industry, which continually produces ever-more sophisticated electronic devices and circuits in response to global demand. Thesemiconductor industry is one of the global economy's largest and most profitableindustries, with annual revenues exceeding $481 billion in 2018. Theelectronics industry also encompasses other branches that rely on electronic devices and systems, such as e-commerce,[citation needed] which generated over $29 trillion in online sales in 2017. Practical electronic systems commonly combine analog and digital techniques, using analog front ends with digital processing.[4]
Vacuum tubes (thermionic valves) were the first activeelectronic components which controlledcurrent flow by influencing the flow of individualelectrons, and enabled the construction of equipment that used current amplification and rectification to give usradio,television,radar, long-distance telephony and much more. The early growth of electronics was rapid, and by the 1920s, commercialradio broadcasting andtelecommunications were becoming widespread and electronic amplifiers were being used in such diverse applications as long-distancetelephony and the music recording industry.[8]
The next big technological step took several decades to appear, when the first workingpoint-contact transistor was invented byJohn Bardeen andWalter Houser Brattain at Bell Labs in 1947.[9] The 1947 point contact transistor showed that semiconductors could replace many tube functions with lower power and size.[10]However, vacuum tubes continued to play a leading role in the field ofmicrowave and high power transmission as well astelevision receivers until the middle of the 1980s.[11]Since then,solid-state devices have all but completely taken over. Vacuum tubes are still used in some specialist applications such ashigh power RF amplifiers,cathode-ray tubes, specialist audio equipment,guitar amplifiers and somemicrowave devices.
In April 1955, theIBM 608 was the firstIBM product to usetransistor circuits without any vacuum tubes and is believed to be the first all-transistorizedcalculator to be manufactured for the commercial market.[12][13] The 608 contained more than 3,000germanium transistors.Thomas J. Watson Jr. ordered all future IBM products to use transistors in their design. From that time on transistors were almost exclusively used forcomputer logic circuits and peripheral devices. However, earlyjunction transistors were relatively bulky devices that were difficult to manufacture on amass-production basis, which limited them to a number of specialised applications.[14]
TheMOSFET was invented at Bell Labs between 1955 and 1960.[15][16][17][18][19][20] It was the first truly compact transistor that could be miniaturised and mass-produced for a wide range of uses.[14] The MOSFET became the most widely used device in VLSI, enabling compact, low power circuits.[21] Its advantages includehigh scalability,[22] affordability,[23] low power consumption, andhigh density.[24] The MOSFET's scalability and cost made it dominant in modern electronics.[25] It revolutionized theelectronics industry,[26][27] becoming the most widely used electronic device in the world.[28][29] The MOSFET is the basic element in most modern electronic equipment.[30][31]As the complexity of circuits grew, problems arose.[32] One problem was the size of the circuit. A complex circuit like a computer was dependent on speed. If the components were large, the wires interconnecting them must be long. The electric signals took time to go through the circuit, thus slowing the computer.[32] Theinvention of the integrated circuit byJack Kilby andRobert Noyce solved this problem by making all the components and the chip out of the same block (monolith) of semiconductor material. The circuits could be made smaller, and the manufacturing process could be automated. This led to the idea of integrating all components on a single-crystalsilicon wafer, which led to small-scale integration (SSI) in the early 1960s, and then medium-scale integration (MSI) in the late 1960s, followed byVLSI. In 2008, billion-transistor processors became commercially available.[33] Integrated circuits put many components on one chip, shortening interconnects and increase speed.[25]
An electronic component is any component, either active or passive, in anelectronic system orelectronic device. Components are connected together, usually by being soldered to aprinted circuit board (PCB), to create an electronic circuit with a particular function. Components may be packaged singly, or in more complex groups asintegrated circuits. Passive electronic components arecapacitors,inductors,resistors, whilst active components are such as semiconductor devices;transistors andthyristors, which control current flow at electron level.[34]
Electronic circuit functions can be divided into two function groups: analog and digital. A particular device may consist of circuitry that has either or a mix of the two types. Analog circuits are becoming less common, as many of their functions are being digitized.
Analog circuits use a continuous range of voltage or current for signal processing, as opposed to the discrete levels used in digital circuits. Analog circuits were common throughout an electronic device in the early years in devices such as radio receivers and transmitters. Analog electronic computers were valuable for solving problems with continuous variables until digital processing advanced.
As semiconductor technology developed, many of the functions of analog circuits were taken over by digital circuits, and modern circuits that are entirely analog are less common; their functions being replaced by hybrid approach which, for instance, uses analog circuits at thefront end of a device receiving an analog signal, and then use digital processing usingmicroprocessor techniques thereafter.
Sometimes it may be difficult to classify some circuits that have elements of both linear and non-linear operation. An example is the voltage comparator which receives a continuous range of voltage but only outputs one of two levels as in a digital circuit. Similarly, an overdriven transistor amplifier can take on the characteristics of a controlledswitch, having essentially two levels of output.
Analog circuits are still widely used for signal amplification, such as in the entertainment industry, and conditioning signals from analog sensors, such as in industrial measurement and control.
Digital circuits are electric circuits based on discrete voltage levels. Digital circuits useBoolean algebra and are the basis of all digital computers and microprocessor devices. They range from simple logic gates to large integrated circuits, employing millions of such gates.
Digital circuits use abinary system with two voltage levels labelled "0" and "1" to indicated logical status. Often logic "0" will be a lower voltage and referred to as "Low" while logic "1" is referred to as "High". However, some systems use the reverse definition ("0" is "High") or are current based. Quite often the logic designer may reverse these definitions from one circuit to the next as they see fit to facilitate their design. The definition of the levels as "0" or "1" is arbitrary.[35]
Ternary (with three states) logic has been studied, and some prototype computers made, but have not gained any significant practical acceptance.[36] Universally,Computers andDigital signal processors are constructed withdigital circuits usingTransistors such asMOSFETs in the electronic logic gates to generate binary states.
A selection of logic gates, used extensively in digital electronics
Electronic systems design deals with the multi-disciplinary design issues of complex electronic devices and systems, such asmobile phones andcomputers. The subject covers a broad spectrum, from the design and development of an electronic system (new product development) to assuring its proper function, service life anddisposal.[37] Electronic systems design is therefore the process of defining and developing complex electronic devices to satisfy specifiedrequirements of the user.
Due to the complex nature of electronics theory, laboratory experimentation is an important part of the development of electronic devices. These experiments are used to test or verify the engineer's design and detect errors. Historically, electronics labs have consisted of electronics devices and equipment located in a physical space, although in more recent years the trend has been towardselectronics lab simulation software, such asCircuitLogix,Multisim, andPSpice.
Today's electronics engineers have the ability todesigncircuits using premanufactured building blocks such aspower supplies,semiconductors (i.e. semiconductor devices, such as transistors), and integrated circuits.Electronic design automation software programs includeschematic capture programs and printed circuit board design programs. Popular names in the EDA software world are NI Multisim,Cadence (ORCAD),EAGLE PCB[38] and Schematic,Mentor (PADS PCB and LOGIC Schematic),Altium (Protel), LabCentre Electronics (Proteus),gEDA,KiCad and many others.
Electronic noise is defined[39] as unwanted disturbances superposed on a useful signal that tend to obscure its information content. Noise is not the same as signal distortion caused by a circuit. Noise is associated with all electronic circuits. Noise may be electromagnetically or thermally generated, which can be decreased by lowering theoperating temperature of the circuit. Other types of noise, such asshot noise cannot be removed as they are due to limitations in physical properties.
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Through-hole devices mounted on the circuit board of a mid-1980shome computer. Axial-lead devices are at upper left, while blue radial-lead capacitors are at upper right.
Many different methods of connecting components have been used over the years. For instance, early electronics often usedpoint to point wiring with components attached to wooden breadboards to construct circuits.Cordwood construction andwire wrap were other methods used. Most modern-day electronics now use printed circuit boards made of materials such asFR-4 andFR-2. Modern PCBs are usually FR-4 epoxy boards with through hole or surface mount parts.[40] Electrical components are generally mounted to PCBs usingthrough-hole orsurface mount.
Health and environmental concerns associated with electronics assembly have gained increased attention in recent years.
However, during the 1990s and subsequently, the industry shifted overwhelmingly to East Asia (a process begun with the initial movement ofmicrochip mass-production there in the 1970s), as plentiful, cheap labor, and increasing technological sophistication, became widely available there.[46][47]
Over three decades, the United States' global share of semiconductor manufacturing capacity fell, from 37% in 1990, to 12% in 2022.[47] America's pre-eminent semiconductor manufacturer,Intel Corporation, fell far behind its subcontractorTaiwan Semiconductor Manufacturing Company (TSMC) in manufacturing technology.[46]
Important semiconductor industry facilities (which often are subsidiaries of a leading producer based elsewhere) also exist in Europe (notably theNetherlands), Southeast Asia, South America, andIsrael.[46]
^Guarnieri, M. (2012). "The age of vacuum tubes: Early devices and the rise of radio communications".IEEE Industrial Electronics Magazine 6 (1): 41–43.doi:10.1109/MIE.2012.2182822.
^Grant, Duncan Andrew; Gowar, John (1989).Power MOSFETS: theory and applications.Wiley. p. 1.ISBN978-0471828679.Archived from the original on 30 July 2020. Retrieved10 August 2019.The metal–oxide–semiconductor field-effect transistor (MOSFET) is the most commonly used active device in the very large-scale integration of digital integrated circuits (VLSI). During the 1970s these components revolutionized electronic signal processing, control systems and computers.
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