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Portal:Electronics

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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. It is a subfield of physics and electrical engineering which uses 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 signals to digital signals. Electronics is often contrasted with electrical power engineering, which focuses on generation, transmission, and distribution of electric power rather than signal processing or device level control.

Electronic devices have significantly influenced the development of many aspects of modern society, such as telecommunications, entertainment, education, health care, industry, and security. The main driving force behind the advancement of electronics is the semiconductor industry, which continually produces ever-more sophisticated electronic devices and circuits in response to global demand. The semiconductor industry is one of the global economy's largest and most profitable industries, with annual revenues exceeding $481 billion in 2018. The electronics industry also encompasses other branches that rely on electronic devices and systems, such as e-commerce, 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. (Full article...)

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This 90-foot (27m) diameter radar installation monitors the northern Alaskan sky.

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Charles Augustin de Coulomb (June 14, 1736 – August 23, 1806) was a French physicist, born in Angoulême, France. Coulomb is distinguished in the history of mechanics and of electricity and magnetism. Coulomb explained the laws of attraction and repulsion between electric charges and magnetic poles, although he did not find any relationship between the two phenomena. He thought that the attraction and repulsion were due to different kinds of fluids. The SI unit of charge, the coulomb, and Coulomb's law are named after him.

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Printed circuit planar transmission lines used to create filters in a 20 GHz spectrum analyser. The structure on the left is called a hairpin filter and is an example of a band-pass filter. The structure on the right is a stub filter and is a low-pass filter. The perforated regions above and below are not transmission lines, but electromagnetic shielding for the circuit.

Planar transmission lines are transmission lines with conductors, or in some cases dielectric (insulating) strips, that are flat, ribbon-shaped lines. They are used to interconnect components on printed circuits and integrated circuits working at microwave frequencies because the planar type fits in well with the manufacturing methods for these components. Transmission lines are more than simply interconnections. With simple interconnections, the propagation of the electromagnetic wave along the wire is fast enough to be considered instantaneous, and the voltages at each end of the wire can be considered identical. If the wire is longer than a large fraction of a wavelength (one tenth is often used as a rule of thumb), these assumptions are no longer true and transmission line theory must be used instead. With transmission lines, the geometry of the line is precisely controlled (in most cases, the cross-section is kept constant along the length) so that its electrical behaviour is highly predictable. At lower frequencies, these considerations are only necessary for the cables connecting different pieces of equipment, but at microwave frequencies the distance at which transmission line theory becomes necessary is measured in millimetres. Hence, transmission lines are needed within circuits.

The earliest type of planar transmission line was conceived during World War II by Robert M. Barrett. It is known as stripline, and is one of the four main types in modern use, along with microstrip, suspended stripline, and coplanar waveguide. All four of these types consist of a pair of conductors (although in three of them, one of these conductors is the ground plane). Consequently, they have a dominant mode of transmission (the mode is the field pattern of the electromagnetic wave) that is identical, or near-identical, to the mode found in a pair of wires. Other planar types of transmission line, such as slotline, finline, and imageline, transmit along a strip of dielectric, and substrate-integrated waveguide forms a dielectric waveguide within the substrate with rows of posts. These types cannot support the same mode as a pair of wires, and consequently they have different transmission properties. Many of these types have a narrower bandwidth and in general produce more signal distortion than pairs of conductors. Their advantages depend on the exact types being compared, but can include low loss and a better range of characteristic impedance. (Full article...)

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iPod is a brand of portable media players designed and marketed by Apple Computer and launched in 2001. Devices in the iPod range are primarily music players, designed around a central scroll wheel. The full-sized model stores media on an internal hard drive, while the smaller iPod nano and iPod shuffle use flash memory. Like many digital audio players, iPods can also serve as external data storage devices.

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