OCXO (Oven Controlled Crystal Oscillators)

An oven-controlled crystal oscillator (OCXO) is a precision timing component that encloses a quartz crystal within a temperature-regulated chamber, holding it at a fixed elevated temperature, typically between 75°C and 80°C, to eliminate frequency drift caused by ambient thermal variation. This thermal isolation makes OCXOs the highest-stability option in the crystal oscillator family, offering frequency stabilities as tight as ±800 ppt.

OCXOs are specified in applications where consistent, long-term frequency accuracy is non-negotiable: telecommunications infrastructure, defense electronics, satellite systems, and industrial test and measurement. Their built-in heater and thermal insulation make them physically larger than TCXOs or standard crystal oscillators, but no other crystal-based solution matches their performance under adverse or fluctuating temperature conditions.

Suntsu’s frequency control portfolio spans the full spectrum of timing components. Engineers sourcing complementary devices can explore our crystal oscillators, TCXO, and VCXO offerings, or view the complete frequency control product line.

Standard OCXOs: Our standard OCXO oscillators ship in through-hole packages and cover a broad range of output frequencies, supply voltages, and logic types. These are suited for production designs requiring proven, catalog-ready high-stability timing without the lead time of a custom build.

High-Stability OCXOs: For applications demanding tighter frequency tolerances, Suntsu offers high-stability OCXO configurations with stability specifications as tight as ±800 ppt. These are commonly used in stratum-level timing systems, GPS disciplining, and military-grade communications hardware. For holdover-capable designs, pair with our Stratum 3/3E oscillators or rubidium oscillators.

Custom-Configured OCXOs: Suntsu supports custom OCXO designs built to application-specific parameters, including non-standard frequencies, voltage requirements, package dimensions, and environmental ratings. Contact our engineering and sales team with your target specifications to initiate a custom quote.

Complementary Timing Devices: When an OCXO is not required, Suntsu offers lower-power alternatives across our crystals, watch crystals, and real-time clocks collections to support the full timing hierarchy of your design.

Selecting the correct OCXO for your application depends on several technical and operational factors:

• Frequency stability requirement: Determine whether your application requires stability in the ppm or ppt range. OCXOs are the appropriate choice when TCXO-grade stability is insufficient.
• Operating temperature range: Confirm that the OCXO’s oven setpoint exceeds the maximum expected ambient temperature of your deployment environment. If external temperatures approach or exceed the oven temperature, frequency regulation will degrade.
• Output frequency and logic compatibility: Match the OCXO’s nominal output frequency, voltage supply, and logic type (CMOS, LVDS, clipped sine) to your system’s clock input specifications.
• Warm-up time and power budget: OCXOs draw peak power during thermal stabilization, typically a few minutes from a cold start. Confirm your power subsystem can accommodate the inrush before stabilization.
• Custom vs. standard part: If no catalog part meets your frequency, stability, or form factor requirements, Suntsu’s engineering team can develop a custom solution. Provide target specs for frequency, stability, supply voltage, package size, and operating range to begin the process.

An OCXO oscillator maintains temperature stability by running a temperature-controlled chamber. The unit keeps quartz crystals at a constant temperature to avoid any variations in frequency. Given that thermal insulation and a heater are required for the quartz crystals to warm up to temperature, an OCXO is physically larger than other crystal units. The thermal insulation serves as a shield to help protect the OCXO from ambient temperature fluctuations, which is why this premium unit is touted for its precision timing.

Clocks that maintain a higher degree of frequency are typically used to synchronize OCXOs. If the OCXO and the clock become unlocked or unsynchronized at any point, then the OCXO reverts to its internal controls to maintain stability during what is known as the holdover period. Thus, OCXO clocks perform consistently over time without interruptions in their timekeeping output.

The most crucial element in ensuring the precision and stability of a crystal’s frequency is an accurate cut. To maximize the performance of an OCXO, setting regular intervals to recalibrate the OCXO will improve its longevity. Also, the buffering circuitry and assembly of the OCXO should reflect attention to detail so that the components of the OCXO facilitate its stable operating temperature.

The typical oven range of temperatures for OCXOs is between 75 and 80 degrees Celsius. Higher temperature ranges may be preferable in certain industrial settings and will depend on the specific application of the OCXO.