# frequency of clock oscillator?

guys till wat frequency is electronic crystal clock ocsillator is available,i think from 1Mhz -200Mhz!!! am i right?

Relevance

Quartz timing crystals are manufactured for frequencies from a few tens of kilohertz to tens of Megahertz.

Overtone circuits can extend that to several hundred MHz.

Packaged oscillators are available which contain the crystal, the oscillator, a driver, and perhaps a frequency divider for lower frequencies. They are available from several hundred MHz down to 1 Hz, with the low end via use of internal dividers. With use of phase locked loops, you can get packaged devices up to 75 GHz.

Better oscillators also include a controlled heater to keep the crystal at a constant temperature to minimize temperature effects.

wikipedia:

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 and receivers. The most common type of piezoelectric resonator used is the quartz crystal, so oscillator circuits designed around them were called "crystal oscillators".

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 between series and parallel resonance, which means that the crystal appears as an inductive reactance in operation. 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 these crystals the series resistance is specified (<100 Ω) instead of the parallel capacitance. To reach higher frequencies, a crystal can be made to vibrate at one of its overtone modes, which occur at multiples of the fundamental resonant frequency. Only odd numbered overtones are used. Such a crystal is referred to as a 3rd, 5th, or even 7th overtone crystal. To accomplish this, the oscillator circuit usually includes additional LC circuits to select the wanted overtone.

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depending upon your requirement various crystal oscillators are available

if u are using early versions of controller or processor like 8051 family and 8085/8086-88 freq. will be 3M Hz to 12 M Hz and more high speed processors like pentium-pro processor uses crystals with more frequency

and of course....

in agreement with u crystal oscillator can not work above 200 Mhz.

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