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What is a TCXO(Temperature Compensate X'tal (crystal) Oscillator)

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gavinray

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With so many crystal oscillators on the market, why can temperature-compensated crystal oscillators survive in the era of high precision?
 

The name says it all.
Precision generally refers to the accuracy at a particular temperature. No matter how accurate the frequency is, it will still change as environmental conditions vary. Temperature compensated oscillators actively adjust the crystal loading to offset the changes made by temperature variation.

Brian.
 

TCXO uses circuit design techniques to Temperature Compensate the output frequency. Better than nothing, electrically.

OCXO uses a die and xtal suspended in an Oven to hold temperature constant, removing the influence. At the cost of baseline power, maybe some interesting microphonics from the "suspended" bit although you'd expect this to be engineered out).

Trades may favor one over the other, the system will have its say.
 

With so many crystal oscillators on the market, why can temperature-compensated crystal oscillators survive in the era of high precision?
Crystal oscillators use, you guessed it, a crystal. The crystal must be piezoelectric. Common piezoelectric crystals are quartz and synthetic titanates.

The electrical frequency is the same as the mechanical crystal oscillation frequency. The mechanical crystal oscillation frequency depends on the mechanical (elastic) properties of the crystal. This is where the temp sensitivity comes it. Quartz has a lower temperature coefficient of expansion but the synthetic titanate ones have greater voltage output.

Although there are many crystals that are piezoelectric, most are not suitable for a frequency source.

So if you want the frequency of the crystal to be very stable, you must reduce the loading on the crystal (hang it by slender wires) and keep the temp constant somehow.
 

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