NationMaster - Encyclopedia: Crystal oscillator

A crystal oscillator is an electronic circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency. This frequency is commonly used to keep track of time (as in quartz wristwatches), to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters. An electronic circuit is an electrical circuit that also contains active electronic devices such as transistors or vacuum tubes. ... This article is about resonance in physics. ... Quartz crystal Synthetic bismuth crystal Insulin crystals Gallium, a metal that easily forms large single crystals A huge monocrystal of potassium dihydrogen phosphate grown from solution by Saint-Gobain for the megajoule laser of CEA. In chemistry and mineralogy, a crystal is a solid in which the constituent atoms, molecules... Piezoelectricity is the ability of crystals, certain ceramic materials, (and to some degree, all materials) to generate a voltage in response to applied mechanical stress. ... FreQuency is a music video game developed by Harmonix and published by SCEI. It was released in November 2001. ... A quartz clock A quartz clock is a timepiece that uses an electronic oscillator which is made up by a quartz crystal to keep precise time. ... In synchronous digital electronics, such as most computers, a clock signal is a signal used to coordinate the actions of two or more circuits. ... A digital system is one that uses discrete values (often electrical voltages), especially those representable as binary numbers, or non-numeric symbols such as letters or icons, for input, processing, transmission, storage, or display, rather than a continuous spectrum of values (ie, as in an analog system). ... An integrated circuit (IC) is a thin chip consisting of at least two interconnected semiconductor devices, mainly transistors, as well as passive components like resistors. ... In communications and information processing, a transmitter (sometimes abbreviated XMTR) is an object (source) which sends information to an observer (receiver). ...

Using an amplifier and feedback, it is an especially accurate form of an electronic oscillator. The crystal used therein is sometimes called a "timing crystal". On schematic diagrams a crystal is labeled Y. Generally, an amplifier is any device that uses a small amount of energy to control a larger amount of energy. ... It has been suggested that this article or section be merged with Feedback loop. ... Cross coupled LC oscillator with output on top An electronic oscillator is an electronic circuit that produces a repetitive electronic signal, often a sine wave or a square wave. ... A schematic of the Washington Metro. ...

1 Crystals for timing purposes
2 Crystal modelling
3 Bode magnitude diagram
4 Temperature effects
5 Crystals and frequency
- 5.1 Commonly used crystal frequencies
6 Series or parallel resonance
7 Spurious frequencies
8 Notation
9 See also
10 External links

Crystals for timing purposes

A miniature 4 MHz quartz crystal enclosed in an hermetically sealed HC-49/US package, used as the resonator in a crystal oscillator.

Inside construction of a modern high performance HC-49 package quartz crystal

A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions. A 4 MHz crystal oscillator. ... A 4 MHz crystal oscillator. ... A megahertz (MHz) is one million (106) hertz, a measure of frequency. ... A crystal oscillator is an electronic device that uses the mechanical resonance of a physical crystal of piezoelectric material to create an electrical signal with a very precise frequency. ... The term hermetically sealed is used to describe something that has an airtight seal. ... Image File history File links Download high-resolution version (1276x1467, 218 KB) Inside construction of a typical HC49 case quartz crystal I, the creator of this work, hereby release it into the public domain. ... Image File history File links Download high-resolution version (1276x1467, 218 KB) Inside construction of a typical HC49 case quartz crystal I, the creator of this work, hereby release it into the public domain. ... A crystal oscillator is an electronic device that uses the mechanical resonance of a physical crystal of piezoelectric material to create an electrical signal with a very precise frequency. ... Quartz crystal Synthetic bismuth crystal Insulin crystals Gallium, a metal that easily forms large single crystals A huge monocrystal of potassium dihydrogen phosphate grown from solution by Saint-Gobain for the megajoule laser of CEA. In chemistry and mineralogy, a crystal is a solid in which the constituent atoms, molecules... For other uses, see Solid (disambiguation). ... Properties In chemistry and physics, an atom (Greek á¼„Ï„Î¿Î¼Î¿Ï‚ or Ã¡tomos meaning indivisible) is the smallest particle still characterizing a chemical element. ... In science, a molecule is a group of atoms in a definite arrangement held together by chemical bonds. ... â€œMultivalentâ€ redirects here. ...

Almost any object made of an elastic material could be used like a crystal, with appropriate transducers, since all objects have natural resonant frequencies of vibration. For example, steel is very elastic and has a high speed of sound. It was often used in mechanical filters before quartz. The resonant frequency depends on size, shape, elasticity, and the speed of sound in the material. High-frequency crystals are typically cut in the shape of a simple, rectangular plate. Low-frequency crystals, such as those used in digital watches, are typically cut in the shape of a tuning fork. For applications not needing very precise timing, a low-cost ceramic resonator is often used in place of a quartz crystal. This article is about resonance in physics. ... The steel cable of a colliery winding tower. ... Elasticity is a branch of physics which studies the properties of elastic materials. ... A tuning fork is a simple metal two-pronged fork with the tines formed from a U-shaped bar of elastic material (usually steel). ...

When a crystal of quartz is properly cut and mounted, it can be made to bend in an electric field, by applying a voltage to an electrode near or on the crystal. This property is known as piezoelectricity. When the field is removed, the quartz will generate an electric field as it returns to its previous shape, and this can generate a voltage. The result is that a quartz crystal behaves like a circuit composed of an inductor, capacitor and resistor, with a precise resonant frequency. (See RLC circuit.) Quartz is one of the most common minerals in the Earths continental crust. ... International safety symbol Caution, risk of electric shock (ISO 3864), colloquially known as high voltage symbol. ... An electrode is an electrical conductor used to make contact with a metallic part of a circuit (e. ... Piezoelectricity is the ability of crystals, certain ceramic materials, (and to some degree, all materials) to generate a voltage in response to applied mechanical stress. ... An inductor is a passive electrical device employed in electrical circuits for its property of inductance. ... Capacitors: SMD ceramic at top left; SMD tantalum at bottom left; through-hole tantalum at top right; through-hole electrolytic at bottom right. ... Resistor symbols (non-European) Resistor symbols (Europe, IEC) Axial-lead resistors on tape. ... An RLC circuit (also known as a resonant circuit or a tuned circuit) is an electrical circuit consisting of a resistor (R), an inductor (L), and a capacitor (C), connected in series or in parallel. ...

Quartz has the further advantage that its size changes very little with temperature. Therefore, the resonant frequency of the plate, which depends on its size, will not change much, either. This means that a quartz clock, filter or oscillator will remain accurate. For critical applications the quartz oscillator is mounted in a temperature-controlled container, called a crystal oven, and can also be mounted on shock absorbers to prevent perturbation by external mechanical vibrations. A Crystal Oven is a temperature-controlled chamber used to maintain constant temperature of electronic crystals, in order to ensure stability of operation. ...

Quartz timing crystals are manufactured for frequencies from a few tens of kilohertz to tens of megahertz. More than two billion (2×10⁹) crystals are manufactured annually. Most are small devices for consumer devices such as wristwatches, clocks, radios, computers, and cellphones. Quartz crystals are also found inside test and measurement equipment, such as counters, signal generators, and oscilloscopes. A kilohertz (kHz) is a unit of frequency equal to 1,000 hertz (1,000 cycles per second). ... MegaHertz (MHz) is the name given to one million (106) Hertz, a measure of frequency. ... This page is about timekeeping devices. ... A wrist watch A clock (from the Latin cloca, bell) is an instrument for measuring time. ... A BlueGene supercomputer cabinet. ... Cellular redirects here. ... A signal generator, also known variously as a test signal generator, tone generator (in audio only), waveform generator, or frequency generator is an electronic instrument that generates repeating electronic signals (in either the analog or digital domains). ... Illustration showing the interior of a cathode-ray tube for use in an oscilloscope. ...

Crystal modelling

A quartz crystal can be modelled as an electrical network with a low impedance (series) and a high impedance (parallel) resonance point spaced closely together. Mathematically the impedance of this network can be written as: Electrical impedance, or simply impedance, is a measure of opposition to a sinusoidal alternating electric current. ... Electrical impedance, or simply impedance, is a measure of opposition to a sinusoidal alternating electric current. ...

$Z(s) = left( {frac{1}{scdot C_1}+scdot L_1+R_1} right) // left( {frac{1}{scdot C_0}} right)$

or,

$Z(s) = frac{s^2 + sfrac{R_1}{L_1} + {omega_s}^2}{s[s^2 + sfrac{R_1}{L_1} + {omega_p}^2]} Rightarrow omega_s = frac{1}{sqrt{L_1 cdot C_1}} quad omega_p = sqrt{frac{C_1+C_0}{L_1 cdot C_1 cdot C_0}}$

where s is the complex frequency ( $s = j ω$ ), $ω s$ is the series resonant frequency in radians per second and $ω p$ is the parallel resonant frequency in radians per second. Some common angles, measured in radians. ...

Adding additional capacitance across a crystal will cause the parallel resonance to shift downward. This can be used to adjust the frequency that a crystal oscillator oscillates at. Crystal manufacturers normally cut and trim their crystals to have a specified resonant frequency with a known 'load' capacitance added to the crystal. For example, a 6 pF 32 kHz crystal has a parallel resonance frequency of 32,768 Hz when a 6.0 pF capacitor is placed across the crystal. Without this capacitance, the resonance frequency is higher than 32,768 Hz.

Bode magnitude diagram

The present Bode magnitude diagram illustrates the fact that crystal oscillators are extremely selective. The Bode plot for a first-order (one-pole) lowpass filter A Bode plot, named after Hendrik Wade Bode, is usually a combination of a Bode magnitude plot and Bode phase plot: A Bode magnitude plot is a graph of log magnitude against log frequency often used in signal processing...

Image File history File links Size of this preview: 725 Ã— 599 pixelsFull resolution (930 Ã— 769 pixel, file size: 19 KB, MIME type: image/png) This is the Bode magnitude diagram of the impedance of a crystal oscillator. ...

Temperature effects

A crystal's frequency characteristic depends on the shape or 'cut' of the crystal. A tuning fork crystal is usually cut such that its frequency over temperature is a parabolic curve centered around 25 °C. This means that a tuning fork crystal oscillator will resonate close to its target frequency at room temperature, but will slow down when the temperature either increases or decreases from room temperature. A common parabolic coefficient for a 32 kHz tuning fork crystal is −0.04 ppm/°C².

$f = f_0[1-0.04 mbox{ppm}(T-T_0)^2]$

In a real application, this means that a clock built using a regular 32 kHz tuning fork crystal will keep good time at room temperature, lose 2 minutes per year at 10 degrees Celsius above (or below) room temperature and lose 8 minutes per year at 20 degrees Celsius above (or below) room temperature.

Crystals and frequency

Schematic symbol and equivalent circuit for a quartz crystal in an oscillator

The crystal oscillator circuit sustains oscillation by taking a voltage signal from the quartz resonator, amplifying it, and feeding it back to the resonator. The rate of expansion and contraction of the quartz is the resonant frequency, and is determined by the cut and size of the crystal. Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... This article is about resonance in physics. ...

A regular timing crystal contains two electrically conductive plates, with a slice or tuning fork of quartz crystal sandwiched between them. During startup, the circuit around the crystal applies a random noise AC signal to it, and purely by chance, a tiny fraction of the noise will be at the resonant frequency of the crystal. The crystal will therefore start oscillating in synchrony with that signal. As the oscillator amplifies the signals coming out of the crystal, the crystal's frequency will become stronger, eventually dominating the output of the oscillator. Natural resistance in the circuit and in the quartz crystal filter out all the unwanted frequencies. City lights viewed in a motion blurred exposure. ... Television signal splitter consisting of a hi-pass and a low-pass filter. ...

One of the most important traits of quartz crystal oscillators is that they can exhibit very low phase noise. In other words, the signal they produce is a pure tone. This makes them particularly useful in telecommunications where stable signals are needed, and in scientific equipment where very precise time references are needed. In an oscillator, phase noise is rapid, short-term, random fluctuations in the phase of a wave, caused by time domain instabilities. ... Pure tone is a single frequency tone with no harmonic content (no overtones). ...

The output frequency of a quartz oscillator is either the fundamental resonance or a multiple of the resonance, called an overtone frequency. In acoustics and telecommunication, the harmonic of a wave is a component frequency of the signal that is an integer multiple of the fundamental frequency. ... An overtone is a sinusoidal component of a waveform, of greater frequency than its fundamental frequency. ...

A typical Q for a quartz oscillator ranges from 10⁴ to 10⁶. The maximum Q for a high stability quartz oscillator can be estimated as Q = 1.6 × 10⁷/f, where f is the resonance frequency in megahertz. This article or section does not cite any references or sources. ...

Environmental changes of temperature, humidity, pressure, and vibration can change the resonant frequency of a quartz crystal, but there are several designs that reduce these environmental effects. These include the TCXO, MCXO, and OCXO (defined below). These designs (particularly the OCXO) often produce devices with excellent short-term stability. The limitations in short-term stability are due mainly to noise from electronic components in the oscillator circuits. Long term stability is limited by aging of the crystal.

Due to aging and environmental factors such as temperature and vibration, it is hard to keep even the best quartz oscillators within one part in 10⁻¹⁰ of their nominal frequency without constant adjustment. For this reason, atomic oscillators are used for applications that require better long-term stability and accuracy. Atomic clock Chip-Scale Atomic Clock Unveiled by NIST An atomic clock is a type of clock that uses an atomic resonance frequency standard as its counter. ...

Although crystals can be fabricated for any desired resonant frequency, within technological limits, in actual practice today engineers design crystal oscillator circuits around relatively few standard frequencies, such as 3.58MHz, 10 MHz, 14.318, 20 MHz, 33.33 Mhz, and 40 MHz. The vast popularity of the 3.58MHz and 14.318MHz crystals is attributed initially to low cost resulting from scale of economy resulting from the popularity of television and the fact that this frequency is involved in synchronizing to the colorburst signal necessary to display color on an NTSC or PAL based television set. Using frequency dividers, frequency multipliers and phase locked loop circuits, it is possible to synthesize any desired frequency from the reference frequency. Mass production is the production of large amounts of standardised products on production lines. ... Colorburst is a signal used to keep the chrominance subcarrier synchronized in a color television signal. ... The references in this article would be clearer with a different and/or consistent style of citation, footnoting or external linking. ... Television encoding systems by nation PAL, short for Phase Alternating Line, is a colour encoding system used in broadcast television systems in large parts of the world. ... Please wikify (format) this article or section as suggested in the Guide to layout and the Manual of Style. ... A frequency multiplier is commonly used in a radio transmitters to multiply the base frequency of the oscillator by a predetermined number. ... Many electronic systems use internal clocks which are required to be phase-aligned to and/or frequency multiples of some external reference clock. ...

Care must be taken to use only one crystal oscillator source when designing circuits to avoid subtle failure modes of metastability in electronics. If this is not possible, the number of distinct crystal oscillators, PLLs, and their associated clock domains should be rigorously minimized, through techniques such as using a subdivision of an existing clock instead of a new crystal source. Each new distinct crystal source needs to be rigorously justified, since each one introduces new, difficult to debug probabilistic failure modes, due to multiple crystal interactions, into equipment. Metastability in electronics is the ability of a non-equilibrium electronic state to persist for a long period of time (see asynchronous circuit). ...

Commonly used crystal frequencies

Frequency (MHz)	Primary uses
32.768 kHz	Real-time clocks, allows binary division to 1 Hz signal (2¹⁵ x 1 Hz); also often used in low-speed low-power circuits
1.8432	UART clock; allows integer division to common baud rates
2.4576	UART clock; allows integer division to common baud rates up to 38400
3.2768	allows binary division to 100 Hz (32768x 100 Hz, or 2¹⁵ x 100 Hz)
3.575611	PAL M color subcarrier
3.579545	NTSC M color subcarrier; very common and cheap, used in many other applications, eg. DTMF generators
3.582056	PAL N color subcarrier
3.686400	UART clock (2x 1.8432 MHz); allows integer division to common baud rates
4.096000	allows binary division to 1 kHz (2¹² x 1 kHz)
4.194304	Real-time clocks, clearly divides to 1 Hz signal (2²² x 1 Hz)
4.433618	PAL B/D/G/H/I and NTSC M4.43 color subcarrier
4.9152	Used in CDMA systems; divided to 1.2288 MHz baseband frequency as specified by J-STD-008
5.068	used in radio transceivers as an IF source
6.144	digital audio systems - DAT, MiniDisc, sound cards; 128x 48 kHz
6.5536	allows binary division to 100 Hz (65536x 100 Hz, or 2¹⁶ x 100 Hz); used also in red boxes
7.15909	NTSC M color subcarrier (2x 3.579545 MHz)
7.3728	UART clock (4x 1.8432 MHz); allows integer division to common baud rates
8.86724	PAL B/G/H color subcarrier (2x 4.433618 MHz)
9.83040	Used in CDMA systems (2x 4.9152); divided to 1.2288 MHz baseband frequency
10.245	used in radio transceivers; mixes with 10.7 MHz subcarrier yielding 455 kHz signal, a common second IF for FM radio and first IF for AM radio [1]
10.700	used in radio transceivers as an IF source
11.0592	UART clock (6x 1.8432 MHz); allows integer division to common baud rates
12.288	digital audio systems - DAT, MiniDisc, sound cards; 256x 48 kHz
13.875	used in some teletext circuits; 2x 6.9375 MHz (clock frequency of PAL B teletext; SECAM uses 6.203125 MHz, NTSC M uses 5.727272 MHz, PAL G uses 6.2031 MHz, and PAL I uses 4.4375 MHz clock)
14.3182	NTSC M color subcarrier (4x 3.579545 MHz). Also common on VGA cards.
14.7456	UART clock (8x 1.8432 MHz); allows integer division to common baud rates
17.734475	PAL B/G/H color subcarrier (4x 4.433618 MHz)
18.432	UART clock (10x 1.8432 MHz); allows integer division to common baud rates
19.6608	Used in CDMA systems (4x 4.9152); divided to 1.2288 MHz baseband frequency
29.4912	UART clock (16x 1.8432 MHz); allows integer division to common baud rates

A real-time clock (RTC) is a computer clock (most often in the form of an integrated circuit chip) that keeps track of the current time even when the computer is turned off. ... A UART or universal asynchronous receiver-transmitter is a piece of computer hardware that translates between parallel bits of data and serial bits. ... In telecommunications and electronics, baud (pronouced /bɔːd/) is a measure of the signaling rate which is the number of changes to the transmission media per second in a modulated signal. ... A UART or universal asynchronous receiver-transmitter is a piece of computer hardware that translates between parallel bits of data and serial bits. ... Television encoding systems by nation PAL, short for Phase Alternating Line, is a colour encoding system used in broadcast television systems in large parts of the world. ... There are several broadcast television systems in use in the world today. ... A subcarrier is separate analog or digital signal carried on a main radio transmission, which carries extra information such as voice or data. ... The references in this article would be clearer with a different and/or consistent style of citation, footnoting or external linking. ... Dual-tone multi-frequency (DTMF), also known as Touch Tone® is used for telephone signaling over the line in the voice frequency band to the call switching center. ... Television encoding systems by nation PAL, short for Phase Alternating Line, is a colour encoding system used in broadcast television systems in large parts of the world. ... There are several broadcast television systems in use in the world today. ... A UART or universal asynchronous receiver-transmitter is a piece of computer hardware that translates between parallel bits of data and serial bits. ... A real-time clock (RTC) is a computer clock (most often in the form of an integrated circuit chip) that keeps track of the current time even when the computer is turned off. ... Television encoding systems by nation PAL, short for Phase Alternating Line, is a colour encoding system used in broadcast television systems in large parts of the world. ... There are several broadcast television systems in use in the world today. ... General Information Generically (as a multiplexing scheme), code division multiple access (CDMA) is any use of any form of spread spectrum by multiple transmitters to send to the same receiver on the same frequency channel at the same time without harmful interference. ... An intermediate frequency (IF) is a frequency to which a carrier frequency is shifted as an intermediate step in transmission or reception. ... Digital audio tape can also refer to a compact cassette with digital storage. ... See also IBMs VM operating system family, where minidisk refers to a logical unit of storage. ... A sound card is a computer expansion card that can input and output sound under program control. ... A red box is an illegal phreaking toll fraud device that generates tones to simulate inserting coins in pay phones, thus fooling the system into completing free calls. ... A UART or universal asynchronous receiver-transmitter is a piece of computer hardware that translates between parallel bits of data and serial bits. ... In telecommunications and electronics, baud (pronouced /bɔːd/) is a measure of the signaling rate which is the number of changes to the transmission media per second in a modulated signal. ... General Information Generically (as a multiplexing scheme), code division multiple access (CDMA) is any use of any form of spread spectrum by multiple transmitters to send to the same receiver on the same frequency channel at the same time without harmful interference. ... An intermediate frequency (IF) is a frequency to which a carrier frequency is shifted as an intermediate step in transmission or reception. ... FM radio is a broadcast technology invented by Edwin Howard Armstrong that uses frequency modulation to provide high-fidelity sound over broadcast radio. ... Mediumwave radio transmissions (sometimes called Medium frequency or MF) are those between the frequencies of 300 kHz and 3000 kHz. ... An intermediate frequency (IF) is a frequency to which a carrier frequency is shifted as an intermediate step in transmission or reception. ... A UART or universal asynchronous receiver-transmitter is a piece of computer hardware that translates between parallel bits of data and serial bits. ... Digital audio tape can also refer to a compact cassette with digital storage. ... See also IBMs VM operating system family, where minidisk refers to a logical unit of storage. ... A sound card is a computer expansion card that can input and output sound under control of computer programs. ... A BBC Ceefax page from January 9, 2007. ... VGA Port VGA plug Video Graphics Array (VGA) is an analog computer display standard first marketed in 1987 by IBM. It has been technologically outdated in the PC market for some time. ... A UART or universal asynchronous receiver-transmitter is a piece of computer hardware that translates between parallel bits of data and serial bits. ... A UART or universal asynchronous receiver-transmitter is a piece of computer hardware that translates between parallel bits of data and serial bits. ... General Information Generically (as a multiplexing scheme), code division multiple access (CDMA) is any use of any form of spread spectrum by multiple transmitters to send to the same receiver on the same frequency channel at the same time without harmful interference. ... A UART or universal asynchronous receiver-transmitter is a piece of computer hardware that translates between parallel bits of data and serial bits. ...

Series or parallel resonance

A quartz crystal provides both series and parallel resonance. The series resonance is a few kilohertz lower than the parallel one. Crystals below 30 MHz are generally operated at parallel resonance, which means that the crystal impedance appears infinite. Any additional circuit capacitance will thus pull the frequency down. For a parallel resonance crystal to operate at its specified frequency, the electronic circuit has to provide a total parallel capacitance as specified by the crystal manufacturer.

Crystals above 30 MHz (up to >200 MHz) are generally operated at series resonance where the impedance appears at its minimum and equal to the series resistance. For this reason the series resistance is specified (<100 Ω) instead of the parallel capacitance. For the upper frequencies, the crystals are operated at one of its overtones, presented as being a fundamental, 3rd, 5th, or even 7th overtone crystal. The oscillator electronic circuits usually provides additional LC circuits to select the wanted overtone of a crystal. An overtone is a sinusoidal component of a waveform, of greater frequency than its fundamental frequency. ...

Spurious frequencies

For crystals operated in series resonance, significant (and temperature-dependent) spurious responses may be experienced. These responses typically appear some tens of kilohertz above the wanted series resonance. Even if the series resistances at the spurious resonances appear higher than the one at wanted frequency, the oscillator may lock at a spurious frequency (at some temperatures). This is generally avoided by using low impedance oscillator circuits to enhance the series resistance difference.

Notation

On electrical schematic diagrams, crystals are designated with the class letter "Y" (Y1, Y2, etc.) Oscillators, whether they are crystal oscillators or other, are designated with the class letter "G" (G1, G2, etc.) (See IEEE Std 315-1975, or ANSI Y32.2-1975) On occasion, one may see a crystal designated on a schematic with "X" or "XTAL", or a crystal oscillator with "XO", but these forms are deprecated. The Institute of Electrical and Electronics Engineers or IEEE (pronounced as eye-triple-ee) is an international non-profit, professional organization incorporated in the State of New York, United States. ... The American National Standards Institute (ANSI) is a private, non-profit standards organization that produces industrial standards in the United States. ...

Crystal oscillator types and their abbreviations:

ATCXO — analog temperature controlled crystal oscillator
CDXO —calibrated dual crystal oscillator
MCXO — microcomputer-compensated crystal oscillator
OCVCXO — oven-controlled voltage-controlled crystal oscillator
OCXO — oven-controlled crystal oscillator
RbXO — rubidium crystal oscillators (RbXO), a crystal oscillator (can be a MCXO) synchronized with a built-in rubidium standard which is run only occasionally to save power
TCVCXO — temperature-compensated voltage-controlled crystal oscillator
TCXO — temperature-compensated crystal oscillator
TSXO — temperature-sensing crystal oscillator, an adaptation of the TCXO
VCTCXO — voltage controlled temperature compensated crystal oscillator
VCXO — voltage-controlled crystal oscillator
DTCXO — digital temperature compensated crystal oscillator

This article or section does not cite its references or sources. ... The Commodore 64 was one of the most popular microcomputers of its era, and is the best selling home computer of all time. ... A Crystal Oven is a temperature-controlled chamber used to maintain constant temperature of electronic crystals, in order to ensure stability of operation. ... OCXO (short for Oven Controlled X-tal (Crystal) Oscillator) is a technique used for avoiding temperature changes that affect the resonance frequency of a piezoelectrical crystal. ... General Name, Symbol, Number rubidium, Rb, 37 Chemical series alkali metals Group, Period, Block 1, 5, s Appearance grey white Atomic mass 85. ... A rubidium standard is a frequency standard in which a specified hyperfine transition of electrons in rubidium-87 atoms is used to control the output frequency. ... A voltage-controlled oscillator or VCO is an electronic circuit that uses amplification, feedback, and a resonant circuit to generate a repeating voltage waveform. ...

External links

Introduction to quartz frequency standards

Category: Oscillators

Results from FactBites:

Crystal Oscillator General Information and Product Selection (555 words)
	Crystal Oscillators are oscillators where a quartz crystal is used to provide the primary frequency element.
	A Crystal Oscillator is made up of an amplifier and feedback network that selects a portion of the amplifier output and returns it to the amplifier input.
	Because of the changes in impedance of the quartz crystal due to changes in applied frequency, all other components of the circuit should be considered constant reactance resulting in an adjustment of the quartz crystal frequency to a reactance that satisfies the loop phase characteristics.

Crystal Oscillator - Symmetricom (138 words)
	Crystal oscillators are oscillators where the primary frequency determining element is a quartz crystal.
	Because of the inherent characteristics of the quartz crystal the crystal oscillator may be held to extreme accuracy of frequency stability.
	A high quality quartz crystal oscillator should exhibit unusually high spectral purity at frequencies close to the carrier frequency permitting multiplication to millimeter-wave frequencies with excellent signal-to-noise ratio.

More results at FactBites »

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