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# Crystal oscillator

A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a precise frequency. [1]

175 relations: Absorption band, Aegirine, Alexander M. Nicholson, Allan variance, Aluminium, Aluminium phosphate, Amateur radio, American National Standards Institute, Analog temperature controlled crystal oscillator, Angular frequency, Anisotropy, Anodizing, Atom, Atomic clock, Bell Labs, Berlinite, Bismuth germanate, Bravais lattice, Brazil, Capacitance, Capacitor, Ceramic resonator, Clock, Clock drift, Clock generator, Clock signal, Computer, Cristobalite, Crystal, Crystal filter, Crystal oven, Crystal twinning, Crystallographic defect, Diamagnetism, Digital data, Eddy current, Elasticity (physics), Electric field, Electrical impedance, Electrical reactance, Electrical resistivity and conductivity, Electrode, Electromechanics, Electron hole, Electron paramagnetic resonance, Electronic filter, Electronic oscillator, Electrostriction, Erhard Kietz, Etching, ... Expand index (125 more) »

## Absorption band

According to quantum mechanics, atoms and molecules can only hold certain defined quantities of energy, or exist in specific states.

## Aegirine

Aegirine is a member of the clinopyroxene group of inosilicates.

## Alexander M. Nicholson

Alexander M. Nicholson was an American scientist, most notable for inventing the first crystal oscillator, using a piece of Rochelle salt in 1917 while working at Bell Telephone Laboratories.

## Allan variance

The Allan variance (AVAR), also known as two-sample variance, is a measure of frequency stability in clocks, oscillators and amplifiers, named after David W. Allan and expressed mathematically as \sigma_y^2(\tau).

## Aluminium

Aluminium or aluminum is a chemical element with symbol Al and atomic number 13.

## Aluminium phosphate

Aluminium phosphate (AlPO4) is a chemical compound.

Amateur radio, also known as ham radio, describes the use of radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communication.

## American National Standards Institute

The American National Standards Institute (ANSI) is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States.

## Analog temperature controlled crystal oscillator

In physics, an Analog Temperature Controlled Crystal Oscillator or Analogue Temperature Compensated Crystal Oscillator (ATCXO) uses analog sampling techniques to correct the temperature deficiencies of a crystal oscillator circuit, its package and its environment.

## Angular frequency

In physics, angular frequency ω (also referred to by the terms angular speed, radial frequency, circular frequency, orbital frequency, radian frequency, and pulsatance) is a scalar measure of rotation rate.

## Anisotropy

Anisotropy, is the property of being directionally dependent, which implies different properties in different directions, as opposed to isotropy.

## Anodizing

Anodizing (spelled anodising in British English) is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts.

## Atom

An atom is the smallest constituent unit of ordinary matter that has the properties of a chemical element.

## Atomic clock

An atomic clock is a clock device that uses an electron transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element.

## Bell Labs

Nokia Bell Labs (formerly named AT&T Bell Laboratories, Bell Telephone Laboratories and Bell Labs) is an American research and scientific development company, owned by Finnish company Nokia.

## Berlinite

Berlinite (aluminium phosphate, chemical formula AlPO4 or Al(PO4)) is a rare high-temperature hydrothermal or metasomatic phosphate mineral.

## Bismuth germanate

Bismuth germanium oxide or bismuth germanate is an inorganic chemical compound of bismuth, germanium and oxygen.

## Bravais lattice

In geometry and crystallography, a Bravais lattice, named after, is an infinite array of discrete points in three dimensional space generated by a set of discrete translation operations described by: where ni are any integers and ai are known as the primitive vectors which lie in different directions and span the lattice.

## Brazil

Brazil (Brasil), officially the Federative Republic of Brazil (República Federativa do Brasil), is the largest country in both South America and Latin America.

## Capacitance

Capacitance is the ratio of the change in an electric charge in a system to the corresponding change in its electric potential.

## Capacitor

A capacitor is a passive two-terminal electrical component that stores potential energy in an electric field.

## Ceramic resonator

A ceramic resonator is an electronic component consisting of a piece of a piezoelectric ceramic material with two or more metal electrodes attached.

## Clock

A clock is an instrument to measure, keep, and indicate time.

## Clock drift

Clock drift refers to several related phenomena where a clock does not run at exactly the same rate as a reference clock.

## Clock generator

A clock generator is a circuit that produces a timing signal (known as a clock signal and behaves as such) for use in synchronizing a circuit's operation.

## Clock signal

In electronics and especially synchronous digital circuits, a clock signal is a particular type of signal that oscillates between a high and a low state and is used like a metronome to coordinate actions of digital circuits.

## Computer

A computer is a device that can be instructed to carry out sequences of arithmetic or logical operations automatically via computer programming.

## Cristobalite

The mineral cristobalite is a high-temperature polymorph of silica, meaning that it has the same chemical formula as quartz, SiO2, but a distinct crystal structure.

## Crystal

A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.

## Crystal filter

A crystal filter is an electronic filter that uses quartz crystals for resonators.

## Crystal oven

A crystal oven is a temperature-controlled chamber used to maintain the quartz crystal in electronic crystal oscillators at a constant temperature, in order to prevent changes in the frequency due to variations in ambient temperature.

## Crystal twinning

Crystal twinning occurs when two separate crystals share some of the same crystal lattice points in a symmetrical manner.

## Crystallographic defect

Crystalline solids exhibit a periodic crystal structure.

## Diamagnetism

Diamagnetic materials are repelled by a magnetic field; an applied magnetic field creates an induced magnetic field in them in the opposite direction, causing a repulsive force.

## Digital data

Digital data, in information theory and information systems, is the discrete, discontinuous representation of information or works.

## Eddy current

Eddy currents (also called Foucault currents) are loops of electrical current induced within conductors by a changing magnetic field in the conductor due to Faraday's law of induction.

## Elasticity (physics)

In physics, elasticity (from Greek ἐλαστός "ductible") is the ability of a body to resist a distorting influence and to return to its original size and shape when that influence or force is removed.

## Electric field

An electric field is a vector field surrounding an electric charge that exerts force on other charges, attracting or repelling them.

## Electrical impedance

Electrical impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied.

## Electrical reactance

In electrical and electronic systems, reactance is the opposition of a circuit element to a change in current or voltage, due to that element's inductance or capacitance.

## Electrical resistivity and conductivity

Electrical resistivity (also known as resistivity, specific electrical resistance, or volume resistivity) is a fundamental property that quantifies how strongly a given material opposes the flow of electric current.

## Electrode

An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air).

## Electromechanics

In engineering, electromechanics combines processes and procedures drawn from electrical engineering and mechanical engineering.

## Electron hole

In physics, chemistry, and electronic engineering, an electron hole (often simply called a hole) is the lack of an electron at a position where one could exist in an atom or atomic lattice.

## Electron paramagnetic resonance

Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) spectroscopy is a method for studying materials with unpaired electrons.

## Electronic filter

Electronic filters are circuits which perform signal processing functions, specifically to remove unwanted frequency components from the signal, to enhance wanted ones, or both.

## Electronic oscillator

An electronic oscillator is an electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave.

## Electrostriction

Electrostriction (cf. magnetostriction) is a property of all electrical non-conductors, or dielectrics, that causes them to change their shape under the application of an electric field.

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## Etching

Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio (incised) in the metal.

## Etching (microfabrication)

Etching is used in microfabrication to chemically remove layers from the surface of a wafer during manufacturing.

## Fremont, California

Fremont is a city in Alameda County, California, United States.

## Frequency

Frequency is the number of occurrences of a repeating event per unit of time.

## Frequency divider

A frequency divider, also called a clock divider or scaler or prescaler, is a circuit that takes an input signal of a frequency, f_, and generates an output signal of a frequency: f_.

## Frequency multiplier

In electronics, a frequency multiplier is an electronic circuit that generates an output signal whose output frequency is a harmonic (multiple) of its input frequency.

## Frequency synthesizer

A frequency synthesizer is an electronic circuit that generates a range of frequencies from a single reference frequency.

## Frequency-shift keying

Frequency-shift keying (FSK) is a frequency modulation scheme in which digital information is transmitted through discrete frequency changes of a carrier signal.

## G-force

The gravitational force, or more commonly, g-force, is a measurement of the type of acceleration that causes a perception of weight.

## G. W. Pierce

George Washington Pierce (January 11, 1872 – August 25, 1956) was an American physicist.

## Gallium arsenide

Gallium arsenide (GaAs) is a compound of the elements gallium and arsenic.

## Gallium phosphate

Gallium phosphate (GaPO4 or gallium orthophosphate) is a colorless trigonal crystal with a hardness of 5.5 on the Mohs scale.

## GPS disciplined oscillator

A GPS clock, or GPS disciplined oscillator (GPSDO), is a combination of a GPS receiver and a high-quality, stable oscillator such as a quartz or rubidium oscillator whose output is controlled to agree with the signals broadcast by GPS and GNSS satellites.

## Harmonic

A harmonic is any member of the harmonic series, a divergent infinite series.

## Hermetic seal

A hermetic seal is any type of sealing that makes a given object airtight (excludes the passage of air, oxygen, or other gases).

## Hertz

The hertz (symbol: Hz) is the derived unit of frequency in the International System of Units (SI) and is defined as one cycle per second.

## Hydrogen

Hydrogen is a chemical element with symbol H and atomic number 1.

## Hydrothermal synthesis

Hydrothermal synthesis includes the various techniques of crystallizing substances from high-temperature aqueous solutions at high vapor pressures; also termed "hydrothermal method".

## Hydroxy group

A hydroxy or hydroxyl group is the entity with the formula OH.

The hydroxyl radical, •OH, is the neutral form of the hydroxide ion (OH−).

## Hysteresis

Hysteresis is the dependence of the state of a system on its history.

## Inclusion (mineral)

In mineralogy, an inclusion is any material that is trapped inside a mineral during its formation.

## Inductance

In electromagnetism and electronics, inductance is the property of an electrical conductor by which a change in electric current through it induces an electromotive force (voltage) in the conductor.

## Inductor

An inductor, also called a coil, choke or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it.

## Inflection point

In differential calculus, an inflection point, point of inflection, flex, or inflection (British English: inflexion) is a point on a continuously differentiable plane curve at which the curve crosses its tangent, that is, the curve changes from being concave (concave downward) to convex (concave upward), or vice versa.

## Infrared spectroscopy

Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) involves the interaction of infrared radiation with matter.

## Institute of Electrical and Electronics Engineers

The Institute of Electrical and Electronics Engineers (IEEE) is a professional association with its corporate office in New York City and its operations center in Piscataway, New Jersey.

## Integrated circuit

An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, normally silicon.

## Iodine

Iodine is a chemical element with symbol I and atomic number 53.

## Ion

An ion is an atom or molecule that has a non-zero net electrical charge (its total number of electrons is not equal to its total number of protons).

## Issac Koga

Issac (Issaku) Koga (December 5, 1899 in Tashiro Village (now Tosu), Saga Prefecture, Japan – September 2, 1982) the eldest of 7 children.

## Jacques Curie

Paul-Jacques Curie (29 October 1855 &ndash; 19 February 1941) was a French physicist and professor of mineralogy at the University of Montpellier.

## Johnson–Nyquist noise

Johnson–Nyquist noise (thermal noise, Johnson noise, or Nyquist noise) is the electronic noise generated by the thermal agitation of the charge carriers (usually the electrons) inside an electrical conductor at equilibrium, which happens regardless of any applied voltage.

## Lanthanum gallium silicate

Lanthanum gallium silicate (referred to as LGS in this article), also known as langasite, has a chemical formula of the form A3BC3D2O14, where A, B, C and D indicate particular cation sites.

## Lapis lazuli

Lapis lazuli, or lapis for short, is a deep blue metamorphic rock used as a semi-precious stone that has been prized since antiquity for its intense color.

## Laplace transform

In mathematics, the Laplace transform is an integral transform named after its discoverer Pierre-Simon Laplace.

## Laser trimming

Laser trimming is the manufacturing process of using a laser to adjust the operating parameters of an electronic circuit.

## LC circuit

An LC circuit, also called a resonant circuit, tank circuit, or tuned circuit, is an electric circuit consisting of an inductor, represented by the letter L, and a capacitor, represented by the letter C, connected together.

## Lithium

Lithium (from lit) is a chemical element with symbol Li and atomic number 3.

## Lithium borate

Lithium borate, also known as lithium tetraborate (Li2B4O7), is the lithium salt of boric acid.

## Lithium niobate

Lithium niobate is a compound of niobium, lithium, and oxygen.

## Lithium tantalate

Lithium tantalate (LiTaO3) is a perovskite which possesses unique optical, piezoelectric and pyroelectric properties which make it valuable for nonlinear optics, passive infrared sensors such as motion detectors, terahertz generation and detection, surface acoustic wave applications, cell phones and possibly pyroelectric nuclear fusion.

## Louis Essen

Louis Essen FRS O.B.E. (6 September 1908 &ndash; 24 August 1997) was an English physicist whose most notable achievements were in the precise measurement of time and the determination of the speed of light.

## Magnetic field

A magnetic field is a vector field that describes the magnetic influence of electrical currents and magnetized materials.

## Mechanical equilibrium

In classical mechanics, a particle is in mechanical equilibrium if the net force on that particle is zero.

## Mechanical filter

A mechanical filter is a signal processing filter usually used in place of an electronic filter at radio frequencies.

## Microcomputer

A microcomputer is a small, relatively inexpensive computer with a microprocessor as its central processing unit (CPU).

## Mobile phone

A mobile phone, known as a cell phone in North America, is a portable telephone that can make and receive calls over a radio frequency link while the user is moving within a telephone service area.

## Molecular diffusion

Molecular diffusion, often simply called diffusion, is the thermal motion of all (liquid or gas) particles at temperatures above absolute zero.

## Molecule

A molecule is an electrically neutral group of two or more atoms held together by chemical bonds.

Neutron radiation is a form of ionizing radiation that presents as free neutrons.

## Neutron temperature

The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts.

## Noise (electronics)

In electronics, noise is an unwanted disturbance in an electrical signal.

## North American Aviation

North American Aviation (NAA) was a major American aerospace manufacturer, responsible for a number of historic aircraft, including the T-6 Texan trainer, the P-51 Mustang fighter, the B-25 Mitchell bomber, the F-86 Sabre jet fighter, the X-15 rocket plane, and the XB-70, as well as Apollo Command and Service Module, the second stage of the Saturn V rocket, the Space Shuttle orbiter and the B-1 Lancer.

## NTSC

NTSC, named after the National Television System Committee,National Television System Committee (1951–1953),, 17 v. illus., diagrs., tables.

## Optical rotation

Optical rotation or optical activity (sometimes referred to as rotary polarization) is the rotation of the plane of polarization of linearly polarized light as it travels through certain materials.

## Oscilloscope

An oscilloscope, previously called an oscillograph, and informally known as a scope or o-scope, CRO (for cathode-ray oscilloscope), or DSO (for the more modern digital storage oscilloscope), is a type of electronic test instrument that allows observation of varying signal voltages, usually as a two-dimensional plot of one or more signals as a function of time.

## Outgassing

Outgassing (sometimes called offgassing, particularly when in reference to indoor air quality) is the release of a gas that was dissolved, trapped, frozen or absorbed in some material.

## Overtone

An overtone is any frequency greater than the fundamental frequency of a sound.

## Paul Langevin

Paul Langevin (23 January 1872 – 19 December 1946) was a prominent French physicist who developed Langevin dynamics and the Langevin equation.

## Pendulum clock

A pendulum clock is a clock that uses a pendulum, a swinging weight, as its timekeeping element.

## Phase noise

In signal processing, phase noise is the frequency domain representation of rapid, short-term, random fluctuations in the phase of a waveform, caused by time domain instabilities ("jitter").

## Phase-locked loop

A phase-locked loop or phase lock loop abbreviated as PLL is a control system that generates an output signal whose phase is related to the phase of an input signal.

## Phonon scattering

Phonons can scatter through several mechanisms as they travel through the material.

## Photoconductivity

Photoconductivity is an optical and electrical phenomenon in which a material becomes more electrically conductive due to the absorption of electromagnetic radiation such as visible light, ultraviolet light, infrared light, or gamma radiation.

## Photolithography

Photolithography, also termed optical lithography or UV lithography, is a process used in microfabrication to pattern parts of a thin film or the bulk of a substrate.

## Pierce oscillator

The Pierce oscillator is a type of electronic oscillator particularly well-suited for use in piezoelectric crystal oscillator circuits.

## Pierre Curie

Pierre Curie (15 May 1859 – 19 April 1906) was a French physicist, a pioneer in crystallography, magnetism, piezoelectricity and radioactivity.

## Piezoelectricity

Piezoelectricity is the electric charge that accumulates in certain solid materials (such as crystals, certain ceramics, and biological matter such as bone, DNA and various proteins) in response to applied mechanical stress.

## Positive feedback

Positive feedback is a process that occurs in a feedback loop in which the effects of a small disturbance on a system include an increase in the magnitude of the perturbation.

## Potassium

Potassium is a chemical element with symbol K (from Neo-Latin kalium) and atomic number 19.

## Potassium sodium tartrate

Potassium sodium tartrate tetrahydrate, also known as Rochelle salt, is a double salt of tartaric acid first prepared (in about 1675) by an apothecary, Pierre Seignette, of La Rochelle, France.

## Potassium tartrate

Potassium tartrate, dipotassium tartrate or argol has formula K2C4H4O6.

## Q factor

In physics and engineering the quality factor or Q factor is a dimensionless parameter that describes how underdamped an oscillator or resonator is, and characterizes a resonator's bandwidth relative to its centre frequency.

## Quartz

Quartz is a mineral composed of silicon and oxygen atoms in a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2.

## Quartz clock

A quartz clock is a clock that uses an electronic oscillator that is regulated by a quartz crystal to keep time.

## Quartz crystal microbalance

A quartz crystal microbalance (QCM) measures a mass variation per unit area by measuring the change in frequency of a quartz crystal resonator.

## Quartz inversion

The room-temperature form of quartz, α-quartz, undergoes a reversible change in crystal structure at 573 °C to form β-quartz.

Radar is an object-detection system that uses radio waves to determine the range, angle, or velocity of objects.

Radiation hardening is the act of making electronic components and systems resistant to damage or malfunctions caused by ionizing radiation (particle radiation and high-energy electromagnetic radiation), such as those encountered in outer space and high-altitude flight, around nuclear reactors and particle accelerators, or during nuclear accidents or nuclear warfare.

Radio is the technology of using radio waves to carry information, such as sound, by systematically modulating properties of electromagnetic energy waves transmitted through space, such as their amplitude, frequency, phase, or pulse width.

## Random number generation

Random number generation is the generation of a sequence of numbers or symbols that cannot be reasonably predicted better than by a random chance, usually through a hardware random-number generator (RNG).

## Relative permittivity

The relative permittivity of a material is its (absolute) permittivity expressed as a ratio relative to the permittivity of vacuum.

## Resistor

A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element.

## Resonance

In physics, resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at specific frequencies.

## Resonator

A resonator is a device or system that exhibits resonance or resonant behavior, that is, it naturally oscillates at some frequencies, called its resonant frequencies, with greater amplitude than at others.

## RLC circuit

An RLC circuit is an electrical circuit consisting of a resistor (R), an inductor (L), and a capacitor (C), connected in series or in parallel.

## Rockwell International

Rockwell International was a major American manufacturing conglomerate in the latter half of the 20th century, involved in aircraft, the space industry, both defense-oriented and commercial electronics, automotive and truck components, printing presses, valves and meters, and industrial automation.

## Rubidium

Rubidium is a chemical element with symbol Rb and atomic number 37.

## Rubidium standard

A rubidium standard or rubidium atomic clock is a frequency standard in which a specified hyperfine transition of electrons in rubidium-87 atoms is used to control the output frequency.

## Seed crystal

A seed crystal is a small piece of single crystal or polycrystal material from which a large crystal of typically the same material is to be grown in a laboratory.

## Shock (mechanics)

A mechanical or physical shock is a sudden acceleration caused, for example, by impact, drop, kick, earthquake, or explosion.

## Signal generator

A signal generator is an electronic device that generates repeating or non-repeating electronic signals in either the analog or the digital domain.

## Signal-to-noise ratio

Signal-to-noise ratio (abbreviated SNR or S/N) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise.

## Silicon

Silicon is a chemical element with symbol Si and atomic number 14.

## Silver iodide

Silver iodide is an inorganic compound with the formula AgI. The compound is a bright yellow solid, but samples almost always contain impurities of metallic silver that give a gray coloration. The silver contamination arises because AgI is highly photosensitive. This property is exploited in silver-based photography. Silver iodide is also used as an antiseptic and in cloud seeding.

## Sodium

Sodium is a chemical element with symbol Na (from Latin natrium) and atomic number 11.

## Solid

Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma).

## Sonar

Sonar (originally an acronym for SOund Navigation And Ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels.

## Speed of sound

The speed of sound is the distance travelled per unit time by a sound wave as it propagates through an elastic medium.

## Steel

Steel is an alloy of iron and carbon and other elements.

## Strategic material

Strategic material is any sort of raw material that is important to an individual's or organization's strategic plan and supply chain management.

## Surface acoustic wave

A surface acoustic wave (SAW) is an acoustic wave traveling along the surface of a material exhibiting elasticity, with an amplitude that typically decays exponentially with depth into the substrate.

## Television

Television (TV) is a telecommunication medium used for transmitting moving images in monochrome (black and white), or in colour, and in two or three dimensions and sound.

## Thermoluminescence

Thermoluminescence is a form of luminescence that is exhibited by certain crystalline materials, such as some minerals, when previously absorbed energy from electromagnetic radiation or other ionizing radiation is re-emitted as light upon heating of the material.

## Thin-film thickness monitor

Thin-film thickness monitors, deposition rate controllers, and so on, are a family of instruments used in high and ultra-high vacuum systems.

## Transducer

A transducer is a device that converts energy from one form to another.

## Transmitter

In electronics and telecommunications, a transmitter or radio transmitter is an electronic device which produces radio waves with an antenna.

## Tridymite

Tridymite is a high-temperature polymorph of silica and usually occurs as minute tabular white or colorless pseudo-hexagonal crystals, or scales, in cavities in felsic volcanic rocks.

## Trimmer (electronics)

A trimmer is a miniature adjustable electrical component.

## Tuning fork

A tuning fork is an acoustic resonator in the form of a two-pronged fork with the prongs (tines) formed from a U-shaped bar of elastic metal (usually steel).

## United States dollar

The United States dollar (sign: $; code: USD; also abbreviated US$ and referred to as the dollar, U.S. dollar, or American dollar) is the official currency of the United States and its insular territories per the United States Constitution since 1792.

## Variable-frequency oscillator

A variable frequency oscillator (VFO) in electronics is an oscillator whose frequency can be tuned (i.e., varied) over some range.

## Varicap

In electronics, a varicap diode, varactor diode, variable capacitance diode, variable reactance diode or tuning diode is a type of diode designed to exploit the voltage-dependent capacitance of a reversed-biased p–n junction.

## Vibration

Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point.

## Voltage

Voltage, electric potential difference, electric pressure or electric tension (formally denoted or, but more often simply as V or U, for instance in the context of Ohm's or Kirchhoff's circuit laws) is the difference in electric potential between two points.

## Voltage-controlled oscillator

A microwave (12–18nbspGHz) voltage-controlled oscillator A voltage-controlled oscillator (VCO) is an electronic oscillator whose oscillation frequency is controlled by a voltage input.

## Wafer (electronics)

A wafer, also called a slice or substrate, is a thin slice of semiconductor material, such as a crystalline silicon, used in electronics for the fabrication of integrated circuits and in photovoltaics for conventional, wafer-based solar cells.

Dr.

## Watch

A watch is a timepiece intended to be carried or worn by a person.

## Wavenumber

In the physical sciences, the wavenumber (also wave number or repetency) is the spatial frequency of a wave, measured in cycles per unit distance or radians per unit distance.

## World War II

World War II (often abbreviated to WWII or WW2), also known as the Second World War, was a global war that lasted from 1939 to 1945, although conflicts reflecting the ideological clash between what would become the Allied and Axis blocs began earlier.