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Inside Frequency Control

The 2 Most Important Qualities of an Oven Controlled Crystal Oscillator (OCXO)

Posted by Bliley Technologies on Apr 18, 2024 9:00:00 AM

the 2 most important qualities of an oven controlled crystal oscillator

If you're looking for an oven controlled crystal oscillator (OCXO), my guess is you're interested in the best possible quartz crystal oscillator for your application. Who wouldn't be? 

Oven controlled crystal oscillators are an essential part of many mechanical and electronic devices, but it can get confusing deciding which features and qualities matter most.

We want to make sure you find the very best quality OCXO with the highest standards for your specific needs, so we've narrowed down the many qualities of an OCXO to just the two most important features to look for. In this blog, we'll also cover how these qualities will impact your device’s performance.

The 2 Most Important Qualities of an OCXO

1. High Stability

The signal stability of an OCXO is determined by the crystal's quality factor (or Q factor), which in turn is inversely proportional to the frequency at which the device is designed to operate. The higher the frequency, the less stable the crystal is. That's why most of the research done to develop new OCXO designs focuses on creating oscillators that remain stable even when operating at a high frequencies. 

Some of the factors that influence the Q factor, and consequently the stability of the oscillator, include:

  1. The geometry of the crystal, which refers to the way it is cut and the number of surfaces it possesses.
  2. Mechanical stresses that the crystal may be subjected to over the course of its life. This is an external factor that isn’t decided by the quality of the crystal but rather the conditions under which it is put to use.
  3. The temperature at which the device operates. This closely relates to the number of cuts on the crystal, to the extent that some of the cuts are put in place to control the temperature. 
  4. The purity of the metal and any defects that might have been created deliberately in its composition to improve conductivity.
  5. The presence of a gas that affects the composition of the device through some form of an internal reaction. 
  6. The age of the OCXO. With every fresh operation, the oven controlled crystal oscillator undergoes aging, which negatively affects the device's stability. 

2. Low Phase Noise

The phase noise of an oscillator refers to the frequency domain represented by quick and short fluctuations that occur at random in the phase of a waveform. These fluctuations are a result of time variations that occur during the period in which the signal is processed.

In an ideal oscillator, the wave output of the frequency spectrum would be a line. This kind of an output isn't possible in the real world, so the goal of creating a more efficient oscillator is to keep the output reading as close to a straight line as possible, signaling the generation of low phase noise.

Some of the manufacturing methods that can lead to low phase noise in an OCXO are:

  1. Designing the crystal resonator to produce low phase noise through a combination of voltage control, buffer elements, and stable frequency setting.
  2. Choosing the right materials during OCXO production to ensure there is no frequency interference brought about by the presence of a material that impedes signal frequency.
  3. Extensive in-house testing of the oscillator to ensure the device conforms to the highest standards of excellence in its performance.     
  4. Building the crystal oscillator with as high a Q factor as possible, which results in much cleaner signal processing and consequently, low phase noise. 

Related: 4 Key Questions to Ask to Find the Perfect Crystal Oscillator for Your Design

Find the Best OCXO for Your Next Project

High stability and low phase noise are the two most important properties you must pay attention to when choosing an OCXO. 

Explore our full line of high performance crystal oscillators, including low phase noise and ultra stable models >>


Download our visual guide to the effects of phase noise

Topics: crystal oscillators