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Basic electronics
Published in Raymond F. Gardner, Introduction to Plant Automation and Controls, 2020
Electronic semiconductors are also called solid-state devices. Semiconductors are formed from crystals made of silicon or germanium, which are two periodic-table elements having four valance electrons. Semiconductors are produced by “doping” the pure crystalline-lattice structure with impurities that replace one of the crystalline atoms during the lattice formation. Some doping elements, such as phosphorous or arsenic, produce donor regions at what is called the P-junction. Other doping elements, such as boron or aluminum, produce acceptor regions, which is at the N- junction. The donor region has a shortage of electrons, where the missing valence electrons are called holes, and the acceptor region has a surplus of electrons. The free holes and free electrons are known as charge carriers. In electronics, conventional current is defined as the flow of “holes” or positive charges from the positive voltage-source terminal to the negative or return terminal, which is often the circuit ground. The formation of donor or acceptor patterns tends to allow current to pass more easily in one direction than the other. When germanium is used for the crystalline material, the good-conduction forward-bias voltage drop across the adjacent regions is 0.3V, and when silicon is used, the forward-bias voltage drop is 0.7V. Reverse bias results in very high resistance, essentially becoming a non-conductor.
Nonlinear Circuits
Published in Richard C. Dorf, Circuits, Signals, and Speech and Image Processing, 2018
Jerry L. Hudgins, Theodore F. Bogart, Taan El Ali, Mahamudunnabi Basunia, Kartikeya Mayaram
A diode generally refers to a two-terminal solid-state semiconductor device that presents a low impedance to current flow in one direction and a high impedance to current flow in the opposite direction. These properties allow the diode to be used as a one-way current valve in electronic circuits. Rectifiers are a class of circuits whose purpose is to convert ac waveforms (usually sinusoidal and with zero average value) into a waveform that has a significant nonzero average value (dc component). Simply stated, rectifiers are ac-to-dc energy converter circuits. Most rectifier circuits employ diodes as the principal elements in the energy conversion process; thus the almost inseparable notions of diodes and rectifiers. The general electrical characteristics of common diodes and some simple rectifier topologies incorporating diodes are discussed.
Microelectronics – semiconductor technology
Published in David Jiles, Introduction to the Electronic Properties of Materials, 2017
Transistors are solid-state devices for amplifying and controlling electrical signals (voltages and currents). The bipolar junction transistor (BJT), which was invented at Bell Laboratories in 1947, is the prototype of many important electronic devices and we shall briefly discuss its operation. This consists of two semiconductor junctions, with one semiconductor region common to both, Fig. 11.7. There are two possible configurations, ‘n-p-n’ and ‘p-n-p’. The first transistors were made of germanium because at the time it could be produced in pure form more easily than other semiconducting materials, such as silicon. The region in the middle of this semiconducting ‘sandwich’ is the base. The other two are known as the emitter and collector. All three have direct electrical connections in a circuit.
Stepwise implementation of a low-cost and portable radiofrequency hyperthermia system for in vitro/in vivo cancer studies
Published in Instrumentation Science & Technology, 2021
Fatih Senturk, I. Cengiz Kocum, Goknur Guler Ozturk
The RF hyperthermia system's main component is an RF power generator that operates from 0 to 2 kW and 100 kHz to 100 MHz.[18–20] The high-frequency power metal oxide semiconductor field-effect transistor (MOSFET) provides a solid-state RF source for hyperthermia systems with high efficiency. Solid-state amplifiers are attractive due to their small size, high stability, and careful power control.[21] In radiofrequency systems, it is crucial to use a suitable impedance matching network to control the power and transfer most of the energy from the source to the load.[22] The impedance can be matched to 50 ohms between the output of the source and the load (coil) using passive components, inductors, and capacitors.[23] The hyperthermia system's efficiency also depends on the load (antenna, coil) performance, which transfers radiofrequency energy to the biological samples.[24] Many different coil geometries are used in hyperthermia experiments, including solenoids,[25] pancakes (flat),[26] and Helmholtz[27] coils.
Editor’s message: the solid-state applications era
Published in Journal of Microwave Power and Electromagnetic Energy, 2022
Physics of the solid-state is the science that explains and supports the technology of semiconductor-based electronic devices. It was revolutionary since the first calculating machine based on transistors was built in 1954 followed by thousands of electronic products. ‘Solid-state’ was more than a couple of words stamped on TV sets and radios, among others, about 60 years ago for marketing, rather it was stating their operation structure.