Electronic devices have hugely 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 in response to global demand continually produces ever-more sophisticated electronic devices and circuits. Thesemiconductor industry is one of the largest and most profitable sectors in the global economy, with annual revenues exceeding $481 billion in 2018. The electronics industry also encompasses other sectors that rely on electronic devices and systems, such as e-commerce, which generated over $29 trillion in online sales in 2017.
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.[5]
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.[8][9] 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.[10]
TheMOSFET was invented at Bell Labs between 1955 and 1960.[11][12][13][14][15][16] It was the first truly compact transistor that could be miniaturised and mass-produced for a wide range of uses.[10] Its advantages includehigh scalability,[17] affordability,[18] low power consumption, andhigh density.[19] It revolutionized theelectronics industry,[20][21] becoming the most widely used electronic device in the world.[22][23] The MOSFET is the basic element in most modern electronic equipment.[24][25]
As the complexity of circuits grew, problems arose.[26] 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.[26] 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.[27]
An electronic component is any component in anelectronic system either active or passive. 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.[28]
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.[29]
Ternary (with three states) logic has been studied, and some prototype computers made, but have not gained any significant practical acceptance.[30] 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.[31] 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.
Electronic noise is defined[33] 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.
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 asFR4, or the cheaper (and less hard-wearing) Synthetic Resin Bonded Paper (SRBP, also known as Paxoline/Paxolin (trade marks) and FR2) – characterised by its brown colour. Health and environmental concerns associated with electronics assembly have gained increased attention in recent years, especially for products destined to go to European markets.
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.
Electrical components are generally mounted in the following ways:
Through-hole (sometimes referred to as 'Pin-Through-Hole')
Theelectronics industry consists of various sectors. The central driving force behind the entire electronics industry is thesemiconductor industry sector,[34] which has annual sales of over$481 billion as of 2018.[35] The largest industry sector ise-commerce, which generated over$29 trillion in 2017.[36] Themost widely manufactured electronic device is themetal-oxide-semiconductor field-effect transistor (MOSFET), with an estimated 13sextillion MOSFETs having been manufactured between 1960 and 2018.[37] In the 1960s, U.S. manufacturers were unable to compete with Japanese companies such asSony andHitachi who could produce high-quality goods at lower prices. By the 1980s, however, U.S. manufacturers became the world leaders in semiconductor development and assembly.[38]
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.[39][40]
Over three decades, the United States' global share of semiconductor manufacturing capacity fell, from 37% in 1990, to 12% in 2022.[40] America's pre-eminent semiconductor manufacturer,Intel Corporation, fell far behind its subcontractorTaiwan Semiconductor Manufacturing Company (TSMC) in manufacturing technology.[39]
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.[39]
^Guarnieri, M. (2012). "The age of vacuum tubes: Early devices and the rise of radio communications".IEEE Ind. Electron. M.6 (1):41–43.doi:10.1109/MIE.2012.2182822.S2CID23351454.
^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.
