Frequency Stability: Introduction and Applications - Wiley-IEEE Press Books
Phase locked backward wave oscillator pulsed beam spectrometer in the submillimeter wave range. Schiller, S. Ultra-narrow-linewidth continuous-wave THz sources based on multiplier chains. B 95 , 55—61 Bartalini, S. Barbieri, S.
Phase-locking of a 2. Photonics 4 , — Argence, B. Quantum cascade laser frequency stabilization at the sub-Hz level. Photonics 9 , — Tan, P. Terahertz radiation sources based on free electron lasers and their applications. China Inf. Allaria, E. Highly coherent and stable pulses from the FERMI seeded free-electron laser in the extreme ultraviolet. Photonics 6 , — Glyavin, M.
Terahertz gyrotrons: State of the art and prospects. Thumm, M. Update 6. Gaponov, A. The induced radiation of excited classical oscillators and its use in high-frequency electronics. Quantum Electron. Flyagin, V.
High-power sub-terahertz source with a record frequency stability at up to 1 Hz
The Gyrotron. Theory Tech. Nusinovich, G. Introduction to the physics of gyrotrons. The Johns Hopkins University Press, Geist, T.
- LA BONNE IMPULSION POUR CHAQUE APPLICATION;
- PRODUCT FINDER.
- Quartz oscillators;
Linewidth measurement on a GHz gyrotron. Idehara, T. Accurate frequency measurement of a submillimeter wave gyrotron output using a far-infrared laser as a reference.
Dumbrajs, O. Effect of technical noise on radiation linewidth in free-running gyrotron oscillators. Plasmas 4 , — The K a -band kW continuous wave gyrotron with wide-band fast frequency sweep. Plasma Sci. Tsimring, S.
Electron Beams and Microwave Vacuum Electronics. Amplitude modulation of submillimeter wave gyrotron output. Infrared Millimeter Waves 18 , — Golubiatnikov, G. Gyrotron frequency control by a phase lock system. Bakunin, V. Khutoryan, E. Infrared, Millimeter, Terahertz Waves 38 , — Experimental tests of a GHz gyrotron for spectroscopic applications and diagnostics of various media. Koshelev, M. Molecular gas spectroscopy using radioacoustic detection and high-power coherent subterahertz radiation sources.
Denisov, G. Infrared, Millimeter, Terahertz Waves 36 , — Download references. All the authors analyzed the results, discussed this work, and commented on the manuscript. Correspondence to Andrey Fokin. Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Reprints and Permissions. Nuclear Fusion Crystals are sensitive to shock. The mechanical stress causes a short-term change in the oscillator frequency due to the stress-sensitivity of the crystal, and can introduce a permanent change of frequency due to shock-induced changes of mounting and internal stresses if the elastic limits of the mechanical parts are exceeded , desorption of contamination from the crystal surfaces, or change in parameters of the oscillator circuit.
High magnitudes of shocks may tear the crystals off their mountings especially in the case of large low-frequency crystals suspended on thin wires , or cause cracking of the crystal. Crystals free of surface imperfections are highly shock-resistant; chemical polishing can produce crystals able to survive tens of thousands of g. Crystals suffer from minor short-term frequency fluctuations as well. The main causes of such noise are e. The short-term stability is measured by four main parameters: Allan variance the most common one specified in oscillator data sheets , phase noise, spectral density of phase deviations, and spectral density of fractional frequency deviations.
The effects of acceleration and vibration tend to dominate the other noise sources; surface acoustic wave devices tend to be more sensitive than bulk acoustic wave BAW ones, and the stress-compensated cuts are even less sensitive. The relative orientation of the acceleration vector to the crystal dramatically influences the crystal's vibration sensitivity. Mechanical vibration isolation mountings can be used for high-stability crystals. Phase noise plays a significant role in frequency synthesis systems using frequency multiplication; a multiplication of a frequency by N increases the phase noise power by N 2.
A frequency multiplication by 10 times multiplies the magnitude of the phase error by 10 times. Crystals are somewhat sensitive to radiation damage. Such swept crystals have a very low response to steady ionizing radiation. Ionization produces electron-hole pairs; the holes are trapped in the lattice near the Al atom, the resulting Li and Na atoms are loosely trapped along the Z axis; the change of the lattice near the Al atom and the corresponding elastic constant then causes a corresponding change in frequency. All crystals have a transient negative frequency shift after exposure to an X-ray pulse; the frequency then shifts gradually back; natural quartz reaches stable frequency after 10— seconds, with a negative offset to pre-irradiation frequency, artificial crystals return to a frequency slightly lower or higher than pre-irradiation, swept crystals anneal virtually back to original frequency.
The annealing is faster at higher temperatures. Sweeping under vacuum at higher temperatures and field strength can further reduce the crystal's response to X-ray pulses. Series resistance of swept crystals is unaffected. Increase of series resistance degrades Q; too high increase can stop the oscillations. Neutron radiation induces frequency changes by introducing dislocations into the lattice by knocking out atoms, a single fast neutron can produce many defects; the SC and AT cut frequency increases roughly linearly with absorbed neutron dose, while the frequency of the BT cuts decreases.
Frequency change at low ionizing radiation doses is proportionally higher than for higher doses. High-intensity radiation can stop the oscillator by inducing photoconductivity in the crystal and transistors; with a swept crystal and properly designed circuit the oscillations can restart within 15 microseconds after the radiation burst. Quartz crystals with high levels of alkali metal impurities lose Q with irradiation; Q of swept artificial crystals is unaffected.
Irradiation with higher doses over 10 5 rad lowers sensitivity to subsequent doses. Very low radiation doses below rad have disproportionately higher effect, but this nonlinearity saturates at higher doses. At very high doses, the radiation response of the crystal saturates as well, due to the finite number of impurity sites that can be affected.
Magnetic fields have little effect on the crystal itself, as quartz is diamagnetic ; eddy currents or AC voltages can however be induced into the circuits, and magnetic parts of the mounting and housing may be influenced. After the power-up, the crystals take several seconds to minutes to "warm up" and stabilize their frequency. The oven-controlled OCXOs require usually 3—10 minutes for heating up to reach thermal equilibrium; the oven-less oscillators stabilize in several seconds as the few milliwatts dissipated in the crystal cause a small but noticeable level of internal heating.
Crystals have no inherent failure mechanisms; some have operated in devices for decades. Failures may be, however, introduced by faults in bonding, leaky enclosures, corrosion, frequency shift by aging, breaking the crystal by too high mechanical shock, or radiation-induced damage when nonswept quartz is used. The crystals have to be driven at the appropriate drive level. While AT cuts tend to be fairly forgiving, with only their electrical parameters, stability and aging characteristics being degraded when overdriven, low-frequency crystals, especially flexural-mode ones, may fracture at too high drive levels.
The drive level is specified as the amount of power dissipated in the crystal. Low drive levels are better for higher stability and lower power consumption of the oscillator. Higher drive levels, in turn, reduce the impact of noise by increasing the signal-to-noise ratio.
The stability of AT cut crystals decreases with increasing frequency. For more accurate higher frequencies it is better to use a crystal with lower fundamental frequency, operating at an overtone. Aging decreases logarithmically with time, the largest changes occurring shortly after manufacture. A badly designed oscillator circuit may suddenly begin oscillating on an overtone. In , a train in Fremont, California crashed due to a faulty oscillator. An inappropriate value of the tank capacitor caused the crystal in a control board to be overdriven, jumping to an overtone, and causing the train to speed up instead of slowing down.
The resonator plate can be cut from the source crystal in many different ways. The orientation of the cut influences the crystal's aging characteristics, frequency stability, thermal characteristics, and other parameters. These cuts operate at bulk acoustic wave BAW ; for higher frequencies, surface acoustic wave SAW devices are employed. Image of several crystal cuts .
The T in the cut name marks a temperature-compensated cut, a cut oriented in a way that the temperature coefficients of the lattice are minimal; the FC and SC cuts are also temperature-compensated. The high frequency cuts are mounted by their edges, usually on springs; the stiffness of the spring has to be optimal, as if it is too stiff, mechanical shocks could be transferred to the crystal and cause it to break, and too little stiffness may allow the crystal to collide with the inside of the package when subjected to a mechanical shock, and break.
Strip resonators, usually AT cuts, are smaller and therefore less sensitive to mechanical shocks. At the same frequency and overtone, the strip has less pullability, higher resistance, and higher temperature coefficient. The low frequency cuts are mounted at the nodes where they are virtually motionless; thin wires are attached at such points on each side between the crystal and the leads. The large mass of the crystal suspended on the thin wires makes the assembly sensitive to mechanical shocks and vibrations. The crystals are usually mounted in hermetically sealed glass or metal cases, filled with a dry and inert atmosphere, usually vacuum, nitrogen, or helium.
Plastic housings can be used as well, but those are not hermetic and another secondary sealing has to be built around the crystal. Several resonator configurations are possible, in addition to the classical way of directly attaching leads to the crystal. The gap between the electrodes and the resonator act as two small series capacitors, making the crystal less sensitive to circuit influences. AT cut is usually used, though SC cut variants exist as well.
BVA resonators are often used in spacecraft applications. In the s to s, it was fairly common for people to adjust the frequency of the crystals by manual grinding. The crystals were ground using a fine abrasive slurry, or even a toothpaste, to increase their frequency. The frequency of the crystal is slightly adjustable "pullable" by modifying the attached capacitances. A varactor , a diode with capacitance depending on applied voltage, is often used in voltage-controlled crystal oscillators, VCXO. The crystal cuts are usually AT or rarely SC, and operate in fundamental mode; the amount of available frequency deviation is inversely proportional to the square of the overtone number, so a third overtone has only one-ninth of the pullability of the fundamental mode.
SC cuts, while more stable, are significantly less pullable. On electrical schematic diagrams, crystals are designated with the class letter Y Y1, Y2, etc. Oscillators, whether they are crystal oscillators or others, are designated with the class letter G G1, G2, etc. From Wikipedia, the free encyclopedia. Main article: Crystal oscillator frequencies. See also: Crystal growth. Modern Dictionary of Electronics, 7th Ed. US: Newnes. Newnes Dictionary of Electronics, 4th Ed. Comprehensive Dictionary of Electrical Engineering. US: Springer.
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Patent 4,, , Issue date: November 26, Shinohara; Hideo Iwasaki; Carlos K. Suzuki Bibcode : JaJAP.. Method of sweeping quartz U. Patent 3,, , Issue date: Jan 13, Patent 4,, , Issue date: October 3, Lam, TXC Corporation. Patent 5,, , Issue date: May 30, Whitaker 23 December The electronics handbook. CRC Press. Retrieved 26 April Vig Method and apparatus for compensating for neutron induced frequency shifts in quartz resonators U. Vig, U.
Rosen, Carol Zwick. Robert Everest , New York: American Institute of Physics. Hoffman Materials. Kruse Uncooled infrared imaging arrays and systems. Academic Press. Long Low power temperature-controlled frequency-stabilized oscillator U. Sinha Stress-compensated quartz resonators U. Vig High sensitivity temperature sensor and sensor array U. Electronic oscillators. Barkhausen stability criterion Harmonic oscillator Leeson's equation Nyquist stability criterion Oscillator phase noise Phase noise. Phase-shift oscillator Twin-T oscillator Wien bridge oscillator. Butler oscillator Pierce oscillator Tri-tet oscillator.
Blocking oscillator Multivibrator ring oscillator Pearson—Anson oscillator basic Royer. Cavity oscillator Delay-line oscillator Opto-electronic oscillator Robinson oscillator Transmission-line oscillator Klystron oscillator Cavity magnetron Gunn oscillator. Electronic components. Potentiometer digital Variable capacitor Varicap. Capacitor types Ceramic resonator Crystal oscillator Inductor Parametron Relay reed relay mercury switch. He holds fifteen patents. Log In. My Account. Remember to clear the cache and close the browser window. Search For:. Advanced Search.
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