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Why are crystal oscillators used in clocks instead of RLC circuits?

up vote 14 down vote favorite

The timing of quartz clocks is regulated by a crystal oscillator. This crystal oscillator effectively forms an RLC circuit. If this is so, what properties does a crystal oscillator have that makes it advantageous over an RLC circuit?

2 Answers

up vote 4 down vote accept

While a quartz crystal can be modeled as an RLC circuit, that's not what it actually is.
The cut & dimensions of the crystal cause it to be resonant at a particular frequency and this can be much more accurately determined than a circuit made of discrete R's, L's & C's.

up vote 3 down vote

Crystal oscillators are much more accurate, they are small, have low temperature coefficients and low drift at a low cost.


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Why are crystal oscillators used in clocks instead of RLC circuits?

up vote 14 down vote

The timing of quartz clocks is regulated by a crystal oscillator. This crystal oscillator effectively forms an RLC circuit. If this is so, what properties does a crystal oscillator have that makes it advantageous over an RLC circuit?


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up vote 9 down vote

While a quartz crystal can be modeled as an RLC circuit, that's not what it actually is.
The cut & dimensions of the crystal cause it to be resonant at a particular frequency and this can be much more accurately determined than a circuit made of discrete R's, L's & C's.

edit

Compared to a real RLC, the crystal has a fantastically high Q, which means that the resonant frequency peak is extremely narrow. So, the model "as" an RLC has to include that factor, but such values are unattainable with real components. - no comprende Jan 23 at 2:40

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