OCXO SC Cut Crystal Oscillator: Advantages and Disadvantages

This page covers the advantages and disadvantages of OCXO SC cut crystal oscillators. It compares OCXO advantages and disadvantages of the SC cut crystal oscillator type to other crystal oscillator types.

What is OCXO?

The term OCXO refers to an Oven Controlled Crystal Oscillator. It is widely used in communication devices due to its ability to automatically keep the temperature of the crystal constant, and consequently, the frequency output stable despite ambient temperature variations.

It provides a highly stable frequency output. Figure 1 depicts the inside of an OCXO crystal oscillator type. Refer to OCXO basics and OCXO types for more information.

Advantages of OCXO SC Cut Crystal Oscillator

Figure 2 depicts the temperature versus frequency response curve of all three OCXO types: AT cut, IT cut, and SC cut.

Following are the advantages of the OCXO SC cut type:

• It offers higher frequency stability over a wide temperature range compared to other crystal types.
• It offers a high turning point or higher operating temperature.
• It offers improvement in aging performance which is about 2-3 times better compared to AT cut crystal type.
• It has a lower warm-up time compared to the AT cut type. Hence, it gets settled to the final frequency faster.
• Due to higher Q (Quality factor) performance, it offers better phase noise specification.
• It offers lesser G-sensitivity due to the stress compensation feature.
• The SC crystal is less frequency sensitive against change in physical orientation compared to the AT crystal type.
• The SC cut crystal generates a lower amplitude spurious output when subjected to vibration.

Disadvantages of OCXO SC Cut Crystal Oscillator

Following are the disadvantages of the OCXO SC Cut Crystal Oscillator:

• Due to the high turning point, it has a sharper roll-off at low temperatures, and hence OCXOs are used only in ovenized types of oscillators and not in other configurations such as TCXOs or VCXOs etc.
• Manufacturing costs are high due to increased labor costs. This is because of poorer yields of SC cut compared to AT cut type.
• Delivery or lead time is higher compared to AT cut.