Electronics

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This article is about the technical field. For personal/home-use electronic devices, see consumer electronics. For the journal, see Electronics (magazine).

Modern surface-mount electronic components on a printed circuit board, with a large integrated circuit at the top

Electronics is a scientific and engineering discipline that studies and applies the principles of physics to design, create, and operate devices that manipulate electrons and other electrically charged particles. Electronics is a subfield of electrical engineering, but it differs from it in that it focuses on using active devices such as transistors, diodes, and integrated circuits to control and amplify the flow of electric current and to convert it from one form to another, such as from alternating current (AC) to direct current (DC) or from analog to digital. Electronics also encompasses the fields of microelectronics, nanoelectronics, optoelectronics, and quantum electronics, which deal with the fabrication and application of electronic devices at microscopic, nanoscopic, optical, and quantum scales.

Electronics have a profound impact on various aspects of modern society and culture, such as communication, entertainment, education, health care, industry, and security. The main driving force behind the advancement of electronics is the semiconductor industry, which produces the basic materials and components for electronic devices and circuits. The semiconductor 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.

History and development

See also: History of electronic engineering and Timeline of electrical and electronic engineering

One of the earliest Audion radio receivers, constructed by De Forest in 1914

Electronics has hugely influenced the development of modern society. The identification of the electron in 1897, along with the subsequent invention of the vacuum tube which could amplify and rectify small electrical signals, inaugurated the field of electronics and the electron age.^[1] Practical applications started with the invention of the diode by Ambrose Fleming and the triode by Lee De Forest in the early 1900s, which made the detection of small electrical voltages such as radio signals from a radio antenna possible with a non-mechanical device.

Vacuum tubes (thermionic valves) were the first active electronic components which controlled current flow by influencing the flow of individual electrons,^[2] They were responsible for the electronics revolution of the first half of the twentieth century,^[3][4] They enabled the construction of equipment that used current amplification and rectification to give us radio, television, radar, long-distance telephony and much more. The early growth of electronics was rapid, and by the 1920s, commercial radio broadcasting and communications were becoming widespread and electronic amplifiers were being used in such diverse applications as long-distance telephony and the music recording industry.

The next big technological step took several decades to appear, when the first working point-contact transistor was invented by John Bardeen and Walter Houser Brattain at Bell Labs in 1947.^[5] However, vacuum tubes played a leading role in the field of microwave and high power transmission as well as television receivers until the middle of the 1980s.^[6] Since then, solid-state devices have all but completely taken over. Vacuum tubes are still used in some specialist applications such as high power RF amplifiers, cathode-ray tubes, specialist audio equipment, guitar amplifiers and some microwave devices.

In April 1955, the IBM 608 was the first IBM product to use transistor circuits without any vacuum tubes and is believed to be the first all-transistorized calculator to be manufactured for the commercial market.^[7][8] The 608 contained more than 3,000 germanium 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 for computer logic and peripherals. However, early junction transistors were relatively bulky devices that were difficult to manufacture on a mass-production basis, which limited them to a number of specialised applications.^[9]

The MOSFET (MOS transistor) was invented by Mohamed Atalla and Dawon Kahng at Bell Labs in 1959.^{[10][11][12][13]} The MOSFET was the first truly compact transistor that could be miniaturised and mass-produced for a wide range of uses.^[9] Its advantages include high scalability,^[14] affordability,^[15] low power consumption, and high density.^[16] It revolutionized the electronics industry,^[17][18] becoming the most widely used electronic device in the world.^[12][19] The MOSFET is the basic element in most modern electronic equipment.^[20][21]

As the complexity of circuits grew, problems arose.^[22] 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.^[22] The invention of the integrated circuit by Jack Kilby and Robert 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-crystal silicon wafer, which led to small-scale integration (SSI) in the early 1960s, and then medium-scale integration (MSI) in the late 1960s, followed by VLSI. In 2008, billion-transistor processors became commercially available.^[23]