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In the subfield of electronics, electrical engineers design and test electrical networks (more commonly known as circuits) that take advantage of electromagnetic properties of electrical components or elements (such as resistors, capacitors, inductors, transistors, diodes, semiconductors) to achieve the desired functionality. One of several ubiquitous examples is the tuner circuit, which allows the user of a radio to filterThe term filter may refer to: Filter (chemistry) — a device to separate mixtures Electrostatic Dust Filter Filter (mathematics) — a certain kind of subset of a partially ordered set Filter program — in Unix, any program with standard I/O streams. Any soft out all but a single station, corresponding to a desired signal frequencyFrequency is the measurement of the number of times that a repeated event occurs per unit time. To calculate the frequency, one fixes a time interval, counts the number of occurrences of the event within that interval, and then divides this count by the l.
Electronics really began when Lee de Forest invented the Audion in 1907 (a triode vacuum tube), adding a grid electrode to the Fleming valve, inspired by Edison's electric lamp. Within 10 years, the Audion was in use for radio transmitters and receivers as well as allowing coast to coast telephone calls. Vacuum tubes remained the preferred amplifying device for 40 years, until researchers working for William Schockley at Bell Labs invented the transistor in 1947. In the following years, transistors made a small portable radio possible (Transistor Radio), as well as allowing more powerful mainframe computers to be built, since transistors were cooler and required lower voltages than vacuum tubes.
Before the invention of the integrated circuitAn integrated circuit (IC is a thin chip consisting of thousands or millions of interconnected semiconductor devices, mainly transistors, as well as passive components like resistors. As of 2004, typical chips are of size 1 cm2 or smaller, but larger ones, electronic circuits were constructed from discrete components that could be manipulated by hand. These non-integrated circuits consume much space and electrical power, are prone to failure, and are limited in speed, though they are still common in simple applications. The integrated circuitAn integrated circuit (IC is a thin chip consisting of thousands or millions of interconnected semiconductor devices, mainly transistors, as well as passive components like resistors. As of 2004, typical chips are of size 1 cm2 or smaller, but larger ones, by contrast, packs large numbers--often millions--of tiny electrical components, mainly transistors, onto a small chip which is typically the size of a coin. The thought of hand-assembling millions of elements into a small, reliable assembly should be enough to convince one that the integrated circuit is responsible for the technologicalTechnology ( Gr. tau;εχνολογια < τεχνη "craftsmanship" + λογος "word, reckoning" + the suffix ια) has more than one definition. revolution experienced in the latter half of the twentieth century.
In designing an integrated circuit, electrical engineers first construct circuit schematics (drawings) that specify electrical components and describe interconnections among the electrical components. When the schematics are deemed good, electrical engineers convert the schematics into actual layouts, which literally map out layers of various conductor and semiconductor materials (such as metal and polysilicon) on a scale of micrometers and nanometers. The conversion from schematics to layouts can be done by computer programs, although very often human fine-tuning is desirable to decrease space and power consumption.
The physical fabrication of integrated circuits is itself a huge subfield of electrical engineering, on which circuit designers must rely. As transistors become tinier--approaching atomic dimensions-- microelectronic circuit designers must involve themselves more and more in the fabrication process.
Software simulation is essential in the design process of electronic circuits, especially integrated circuits (See SPICE). Models of semiconductor materials and electrical components are constructed by fabrication plants ( fabs) and manufacturers of electrical components for the purpose of simulation.