Everything you need to choose between Oven-Controlled and Temperature-Compensated Crystal Oscillators for your precision timing application
| Parameter | OCXO | TCXO |
|---|---|---|
| Temperature Stability | ±0.01–1 ppm | ±0.5–5 ppm |
| Phase Noise @ 10kHz (10MHz) | −155 to −172 dBc/Hz | −130 to −150 dBc/Hz |
| Aging Rate (per year) | ±0.05–0.5 ppm | ±1–3 ppm |
| Power Consumption | 0.5–5 W (steady) | 5–100 mW |
| Warm-up Time | 3–10 minutes | <100 ms |
| Start-up Current | 200–800 mA | <20 mA |
| Package Size | 20–200 cm³ | 0.1–10 cm³ |
| Cost (unit, 1k qty) | $20–$500+ | $1–$30 |
| Operating Temperature | −40°C to +85°C | −40°C to +85°C |
An Oven-Controlled Crystal Oscillator (OCXO) encloses the crystal resonator in a miniature heated oven, maintaining it at a constant elevated temperature (typically +75°C to +85°C) regardless of ambient conditions. This "ovenization" eliminates the primary source of frequency drift — temperature variation — delivering superior stability.
A Temperature-Compensated Crystal Oscillator (TCXO) uses a compensation network (typically a thermistor-resistor network or digital compensation) that generates a voltage to pull the crystal frequency in the opposite direction of its natural temperature drift. This achieves good stability without the power and size overhead of an oven.
Phase noise is often the deciding factor for RF and timing engineers. Here's how OCXO and TCXO compare at key offsets from a 10 MHz carrier:
| Offset | OCXO (typical) | TCXO (typical) | Difference |
|---|---|---|---|
| 1 Hz | −95 dBc/Hz | −80 dBc/Hz | 15 dB |
| 10 Hz | −120 dBc/Hz | −100 dBc/Hz | 20 dB |
| 100 Hz | −145 dBc/Hz | −125 dBc/Hz | 20 dB |
| 1 kHz | −155 dBc/Hz | −140 dBc/Hz | 15 dB |
| 10 kHz | −162 dBc/Hz | −148 dBc/Hz | 14 dB |
| 100 kHz | −165 dBc/Hz | −152 dBc/Hz | 13 dB |
| Application | Recommended | Key Requirement |
|---|---|---|
| 5G Macro Base Station | OCXO | Phase noise < −150 dBc/Hz@10kHz, ±0.01 ppm holdover |
| 5G Small Cell | TCXO | Low power, compact size, ±0.5 ppm sufficient |
| GPS/GNSS Receiver | TCXO | Fast start-up, low power, ±0.5–2 ppm |
| Satellite Communication | OCXO | Ultra-low phase noise, long-term stability |
| Radar System | OCXO | Phase noise critical for detection sensitivity |
| Defense/Military | OCXO | Extreme stability, phase noise, reliability |
| IoT/Embedded | TCXO | Micro-power, tiny package, ±2–5 ppm |
| Test Equipment | OCXO | Reference-grade stability, low phase noise |
| Financial/HFT Trading | OCXO | Microsecond accuracy, PTP grandmaster |
| Wearable/Portable | TCXO | Minimal power budget, small footprint |
For the most demanding applications requiring ±5 ppb stability and −172 dBc/Hz phase noise at 10 kHz offset.
10 MHz ±5.0 ppb −105 dBc/Hz@100Hz 5V / 12VBalanced performance with ±0.1 ppm stability, ideal for 5G infrastructure and test equipment.
10–100 MHz ±0.1 ppm −169 dBc/Hz@10kHz 12VSmaller form factor for space-constrained applications, still delivering ±0.1 ppm stability.
10–100 MHz ±0.1 ppm −170 dBc/Hz@10kHz 5V / 12VOur engineers can recommend the optimal OCXO or TCXO for your specific requirements.
In some applications, yes. Modern DTCXOs achieving ±0.1 ppm stability can replace low-end OCXOs in applications where phase noise is not critical. However, for any application requiring better than ±0.1 ppm stability or phase noise below −150 dBc/Hz@10kHz, an OCXO remains the only viable option.
The oven maintains the crystal at a constant temperature, eliminating thermal fluctuations that cause frequency instabilities. Additionally, OCXOs typically use SC-cut crystals which have inherently better Q-factor and phase noise characteristics than the AT-cut crystals used in TCXOs.
Typical OCXO warm-up to rated stability takes 3–10 minutes, consuming 2–5x the steady-state power during this period. TCXOs reach specification in milliseconds. If your application has frequent power cycling, the warm-up penalty may be unacceptable.
They serve different purposes. A GPSDO uses GNSS signals to discipline an OCXO, combining the OCXO's short-term stability with GNSS long-term accuracy. An OCXO alone provides better short-term phase noise but drifts over days/months. See our Atomic Clock Selection Guide for more details.