Crystal Oscillators 
What is the difference between these two popular crystal oscillators?
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Raghav Kapur - everything RF

Mar 23, 2018

The oscillation frequency of a crystal changes as temperature varies. Both TCXOs (Temperature Compensated Crystal Oscillators) and OCXOs (Oven Controlled Crystal Oscillators) are crystal oscillators who oscillation frequency does not vary as much at high temperatures or when the temperature fluctuates.

Design: A TCXO uses a compensation circuit to counter/compensate for the change in output frequency due to temperature variation.

In an OCXO, the crystal oscillator is placed in an oven that is pre-heated to a higher temperature. This way an external temperature variation will not impact the output frequency of the oscillator. Due to the fact that OCXO's use an oven, they usually bulky and require some time to heat the oven before providing the frequency stability vs temperature variation. They also have higher power requirements as compared to TCXO's as the oven requires a supply voltage to maintain a higher temperature.

Size: Due to the fact that OCXO's use a pre-heated oven, they are usually bulky. TCXO's use an electronic circuit to compensate of the frequency variation as a result of temperature, the electronic circuits are much smaller than the oven, thus TCXO's are usually much smaller in size than OCXO's.

Power Consumption: OCXO's are more expensive than TCXO's due to the additional components - Oven and Supporting Circuitary required to pre-heat the oven.

Cost: The cost of an OCXO is significantly higher than a TCXO as the OCXO has more components - mainly the oven and circuitry required to heat the oven.

Difference Between TCXO and OCXO

Power RequiredLowHigh
Stabilization TimeMarginal (0.1 to 3 sec)Significant (30 sec to 5 min)
Frequency/Temperature StabilityGoodExcellent

Maksim Rodionov  2 weeks ago

All arguments above are correct but it depends on applications. You cannot use TCXOs, for instance, for Mobile Networks, Test & Measurements, or Navigation. TCXO cannot achieve ADEV 1E-13 or Phase Noise -120 dBc/Hz at 1 Hz offset or Freq vsTemp 1E-11, also TCXO cannot provide good Holdover when reference siganl (e.g. GLONASS or GPS) is lost.