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A crystal oscillator is an electronic oscillator circuit that uses a piezoelectric crystal as a frequency-selective element. [1] [2] [3] The oscillator frequency is often 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 and receivers.
Crystal oscillators can be manufactured for oscillation over a wide range of frequencies, from a few kilohertz up to several hundred megahertz.Many applications call for a crystal oscillator frequency conveniently related to some other desired frequency, so hundreds of standard crystal frequencies are made in large quantities and stocked by electronics distributors.
Therefore, the circuit's oscillation frequency is very close to the natural resonant frequency of the tuned circuit, and doesn't depend much on other components in the circuit. The quartz crystal resonators used in crystal oscillators have even higher (10 4 to 10 6) [38] and their frequency is very stable and independent of other circuit ...
These circuits often include phase-locked loops (PLLs) that produce selectable or programmable output frequencies from the upstream MEMS reference frequencies. [2] MEMS oscillators are commonly available as 4- or 6-pin ICs that conform to printed circuit board (PCB) solder footprints previously standardized for quartz crystal oscillators.
A tri-tet oscillator is a crystal-controlled vacuum tube electronic oscillator circuit. It is a type of electron-coupled oscillator (ECO), which uses a tetrode or pentode tube. The tri-tet was introduced by James J. Lamb in the June 1933 issue of QST magazine. [1] In an ECO, the screen grid acts as a plate for the triode oscillator.
Single transistor emitter-follower circuit. The Butler oscillator is a crystal-controlled oscillator that uses the crystal near its series resonance point. They are used where a simple low-cost circuit is needed which can oscillate at high frquencies (>50MHz [1]) by using overtones of a crystal, and also giving low phase noise.
The total capacitance seen from the crystal looking into the rest of the circuit is called the "load capacitance". When a manufacturer makes a "parallel" crystal, a technician uses a Pierce oscillator with a particular fixed load capacitance (often 18 or 20 pF) while trimming the crystal to oscillate at exactly the frequency written on its package.
Due to the sub 1 ppm accuracy of this type of crystal oscillator specialist packaging must be used to ensure good ageing and temperature shock characteristics. Example applications are for use in low power or battery operated consumer electronic products such as GSM or CDMA mobile phones, or GPS satellite navigation systems.