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Topic: Crystal oscillator


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  Crystal Oscillator General Information and Product Selection
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.
www.oscilent.com /catalog/Category/crystal_oscillator.htm   (555 words)

  
 Crystal Oscillator - Symmetricom
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.
www.symmttm.com /crystal-oscillators.html   (138 words)

  
  CRYSTAL OSCILLATOR
They oscillate at extremely precise high frequencies and are used as clocking devices.
In this effect, when a voltage is applied to a crystal it distorts, producing a resonant frequency.
Crystals are designated by the symbol ‘X’ while the oscillator is given the designation ‘XO’.
www.partminer.com /glossaryhtml/crystal_oscillator.html   (313 words)

  
  Temperature compensated crystal oscillator and method of manufacturing the same - Patent 6661163
A temperature compensated crystal oscillator is manufactured by placing a ring-shaped board on a main board to surround compensating components on the main board, and placing a crystal package on the ring-shaped board.
The temperature compensated crystal oscillator as set forth in claim, 5, wherein the ring-shaped board has a rectangular structure, and the conductive pad is positioned at each of four corners of the ring-shaped board.
A crystal oscillator employing a quartz oscillator is an essential component used to generate an oscillation frequency for controlling transmission and reception of signals between mobile communication terminals, and is superior to other oscillators in terms of frequency stability.
www.freepatentsonline.com /6661163.html   (3013 words)

  
  Oscillator Technology
Quartz crystal oscillator is a timing device consisting of quartz crystal resonator and an oscillation circuit to generate an output waveform at specified frequency.
In a well-designed oscillator the frequency stability vs. temperature is determined primarily by the temperature characteristic of the crystal, and the oscillator manufacturer must select the crystal characteristics that conform to the oscillator circuit to insure that the intrinsic stability of the crystal is not degraded.
In summary, the suitability of double rotated crystals for use in crystal oscillators is essentially restricted to those oven controlled applications where the improved aging, warm-up, and close-in phase noise characteristics justify a significant cost increase.
www.4timing.com /techoscillator.htm   (4829 words)

  
 Crystal oscillator invention   (Site not responding. Last check: )
[0007] In this crystal oscillator, the resonance frequency of crystal resonator 6 is caused to generally match the oscillation frequency of the crystal oscillator.
The crystal resonator is arranged outside the thermostatic oven, and the crystal resonator is designed such that when the temperature of the crystal resonator is at room temperature and the temperature of the crystal unit is, for example, 70.degree.
The crystal oscillator of the present invention has a low level of phase noise and is easily amenable to compact size and low power consumption.
www.freshpatents.com /Crystal-oscillator-dt20051229ptan20050285690.php   (1022 words)

  
 temperature controlled crystal oscillator at Filtronetics, Inc.
A TCXO or temperature controlled crystal oscillator is a crystal oscillator that incorporates circuitry to reduce the natural temperature sensitivity of the crystal.
Of all the crystal oscillator types, the clock oscillator is the simplest and least costly.
A VCXO or voltage controlled crystal oscillator is a crystal oscillator that allows the oscillator frequency to be controlled, "pulled", by an external voltage.
www.filtro.net /temperature_controlled_crystal_oscillator.html   (801 words)

  
 Quartz crystals :: crystal oscillator data from International Crystal
An oscillator is an amplifier with a feedback loop from output to input.
Barkhausen criteria states that for oscillation to occur the product of the gains around a loop must be equal to or greater than unity and that the sum of the phase shifts around the loop must be a multiple of 360°.
The oscillating loop C1 in parallel with R2, Ctrim in parallel with C2 and Rc and the crystal is directly tied to the load causing poor load stability.
www.icmfg.com /crystaloscillatordata.html   (905 words)

  
 Crystal Oscillator MMD Components
A crystal oscillator (sometimes abbreviated to XTAL on schematic diagrams) is an electronic circuit that uses the mechanical resonance of a physical crystal of piezoelectric material along with an amplifier and feedback to create an electrical signal with a very precise frequency.
A crystal oscillator is an especially accurate form of an electronic oscillator.
Crystal oscillators are a common source of time and frequency signals.
www.mmdcomp.com /oscillators-th.htm   (118 words)

  
 How to Choose a Quartz Crystal Oscillator for the MAX1470 Superheterodyne Receiver - Maxim/Dallas
Crystals have two modes of resonance: series (the lower frequency of the two) and parallel (or anti-resonant, the higher of the two).
In this mode, the crystal's total reactance is slightly inductive and is in parallel with the oscillator's load capacitance, forming an LC tank circuit which determines the oscillator frequency.
If a crystal designed to oscillate with a different load capacitance is used, the crystal is pulled away from its stated operating frequency, introducing an error in the reference frequency.
www.maxim-ic.com /appnotes.cfm?appnote_number=1017   (1067 words)

  
 Crystal Oscillator Design Information
While the stability of a crystal oscillator is very much due to the stability of the crystal, the oscillator is also influenced by the circuitry; both must be optimized for best performance.
The primary causes, mass transfer and stress relaxation mechanisms in the crystal unit, can be reduced by maximizing the ratio of quartz resonator mass to contamination mass by minimizing the resonator frequency, and by careful design and processing of the resonators.
Typically, to measure the phase noise of a crystal oscillator an identical tunable oscillator is used as a reference and phase locked to the oscillator being tested.
www.piezotech.com /Technical_Information/AppNotes/Oscillator_Terminology.htm   (1280 words)

  
 Define XO - Crystal Oscillator
Meaning of XO - "Crystal Oscillator", A crystal oscillator is an electronic device that uses the mechanical resonance of a physical crystal of piezo-electric material to create an electrical signal with a very precise frequency.
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.
For the crystal oscillator circuit this means that there is suddenly almost no resistance at all, and that the current frequency is very close to the natural frequency of the crystal.
www.birds-eye.net /definition/x/xo-crystal_oscillator.shtml   (943 words)

  
 An Introduction to Voltage Controlled Crystal Oscillator Design
Voltage controlled crystal oscillators typically employ a varactor diode to vary the frequency of oscillation by application of a tuning voltage.
For PLL systems where the tuning slope impacts the loop stability, it may be appropriate to specify the minimum and maximum tuning slope at all points on the curve in addition to the percent linearity.
The phase noise spectral density is found by multiplying the frequency spectral density, Sy(f), by the carrier frequency squared and dividing by the offset frequency squared.
www.sss-mag.com /cvcxo.html   (797 words)

  
 Electroluminescent Receiver - Crystal Oscillator/Amplifier
The crystal oscillator is switched in unison with the crystal filter, so that the output of the second mixer is always 455kHz.
The advantage of using LEDs is the visual indication of which oscillator is on, helping with diagnosis in case the switching circuit is not operating properly, or in the case of this receiver, ambient light is interfering with the proper operation of the phototransistor.
However, the frequency of the oscillator has to be tuned precisely so that the frequency of the oscillator is close to the series resonant frequency of the one crystal filter, so that the output of the oscillator/amplifier is not lowered a significant amount.
www.qsl.net /wn5y/elrxtalosc.htm   (1403 words)

  
 Hy-Q International Australia - Glossary Of Terms (Oscillators)
Direct compensation: A technique of building crystal oscillators in which the circuit components affecting the crystal load reactance are selected to have temperature characteristics such that the crystal is re-tuned over temperature to reduce the effects of temperature on the frequency of the oscillator.
Phase locked loop: A circuit in which a crystal oscillator is used as a time base for a voltage controlled oscillator maintaining frequency and phase lock between the two oscillators.
This is a useful technique for achieving a frequency programmable crystal oscillator and output frequencies that are out of the range of a crystal manufactured to achieve certain performance specifications.
www.hy-q.com.au /oscillators/osc-glossary.htm   (2589 words)

  
 Mac Crystal Oscillator Speedup History 2.6
Provided the components that are clocked by a particular crystal oscillator are capable of a speed increase, that crystal oscillator may be replaced with one of a higher frequency.
This crystal oscillator swapping has been done for years, and some early computers even had jumpers that made it really easy to disable one oscillator and enable another higher frequency one.
The type of crystal oscillator in the early Mac's is a full size, 14 pin package, TTL type crystal oscillator.
homepage.mac.com /schrier/faq.html   (2558 words)

  
 Oscillators :: oscillator products from International Crystal
If a voltage with a variable frequency is applied to the crystal, the crystal will go into mechanical oscillation and will exhibit a number of resonant frequencies.
ICM crystal oscillators typically have frequency ranges from 32 KHz to 200 MHz.
All ICM custom manufactured crystal oscillators are 100% inspected on state of the art computer-controlled test equipment, not lot inspected, to meet specifications before shipment ensuring customers receive product that functions to required specifications every time ensuring no production downtime, minimizing rework, and eliminating customer returns due to component failure of ICM products.
www.icmfg.com /oscillators.html   (492 words)

  
 Electronics 16
The simplest crystal oscillator is the Pierce oscillator, shown in the figure on the left.
The amplitude of oscillation at the drain was 24 V with R = 1k, the RF voltage across the choke reversing in direction during the cycle.
Other oscillators are discussed on other pages, for example The VTVM and GDO, where the grid-dip oscillator is studied, and Vacuum Tubes, where local oscillators for superheterodynes are presented.
www.du.edu /~etuttle/electron/elect16.htm   (2560 words)

  
 Crystal Oscillator - Symmetricom
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.
symmttm.com /crystal-oscillators.html   (138 words)

  
 voltage controlled crystal oscillator at Filtronetics, Inc.
Premium voltage controlled crystal oscillator: Filtronetics, Inc designs & manufactures frequency control products including high, low, band pass, notch, reject, electronic filters, TCXO, VCXO, and related oscillators and quartz crystals in um-1 and SMD packages in the KHz, MHz and GHz range.
A TCXO or voltage controlled crystal oscillator is a crystal oscillator that incorporates circuitry to reduce the natural temperature sensitivity of the crystal.
voltage controlled crystal oscillators offer better temperature performance than a clock oscillator and are smaller, less costly, use less power, and have no warm-up time like an ovenized oscillator.
www.filtro.net /voltage_controlled_crystal_oscillator.html   (801 words)

  
 pierce_exp
In practical oscillator circuits, the analysis should indicate a loop gain magnitude greater than one, which will cause the amplitude of oscillation to grow exponentially until clipping or other nonlinear phenomena cause the gain magnitude to decrease to unity.
The Pierce oscillator shown above is essentially a common emitter amplifier with a tuned circuit for a collector load and a quartz crystal as a feedback element.
The inductive susceptance of the crystal is reduced slightly by the phase shift capacitor, but the resultant total susceptance is stil inductive, and forms a parallel resonant circuit with the tank circuit which, as mentioned previously, appears capacitive at the crystal frequency.
pr.erau.edu /~lyallj/ee412/pierce_exp.html   (821 words)

  
 Crystal Oscillator operates as low as 1.6 V., Fox Electronics
Crystal Oscillator operates as low as 1.6 V. May 16, 2002 - F4500 offers input voltage of 1.8 V ±5%, frequency range of 30 to 70 MHz, and maximum input current of 15 mA.
Greater system efficiency is achieved through the oscillator's direct connection to the system's processor, which eliminates the extra circuitry previously needed to match the processor's voltage to the oscillator's voltage.
Apr 12, 2005 - Silicon Oscillator operates from —40 to 125°C. Apr 8, 2005 - Crystal Oscillator is suited for mobile communications.
news.thomasnet.com /fullstory/9955   (904 words)

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