SiTime Targets Data Centers and Network Gear With MEMS OXCO Family

In an era where the Internet of Things (IoT), 5G networks, and data centers are becoming ubiquitous, the demand for precise timing solutions has never been more critical. Whereas traditional quartz-based oscillators have long been the industry standard, the technology is quickly becoming unable to meet the stringent requirements of modern electronics.

This week, SiTime announced their Epoch Platform, a new MEMS-based Oven-Controlled Crystal Oscillator (OCXO) that promises to redefine the landscape of precision timing. But what is an OCXO, and what is SiTime bringing to the table?

 

All About Accuracy

In terms of architecture, SiTime’s Epoch Platform is unique in that it integrates unique technologies like DualMEMS temperature sensing, a unique die construction that produces “the world's most accurate temperature sensor,” and TempFlat MEMS.

These additions are said to make Epoch resilient to temperature fluctuations and airflow. Additionally, the family incorporates advanced algorithms and analog circuitry to achieve better dynamic stability and ultra-low phase noise.

 

The Epoch platform offers exceptional timing accuracy. Image used courtesy of SiTime

 

With these innovations, SiTime’s Epoch Platform promises 2× longer holdover time, 9× smaller footprint, and 25× less volume than comparable quartz OCXOs while also offering 3× lower power consumption. With family offerings supporting frequencies from 10 MHz to 220 MHz, the devices offer frequency stabilities of ±1, ±3, ±5 ppb over an operating temperature range of -40 °C to +95 °C. 

By offering longer holdover times and greater resilience to environmental conditions, SiTime intends for Epoch to meet the emerging precision timing demands of modern networks and data centers. Its advantages in size and power consumption also make it ideal for applications beyond telecom, including aerospace and defense—sectors that are increasingly relying on MEMS technology for mission-critical operations.

 

Oscillators and OCXOs

In electronic systems, oscillators serve as the timing element, generating a periodic waveform that acts as a clock signal to synchronize various components. While basic quartz oscillators are sufficient for many applications, they are susceptible to frequency drift due to environmental factors like temperature changes, vibration, and humidity.

Oven-Controlled Crystal Oscillators (OXCOs) are a specialized class of oscillators that offer superior frequency stability by maintaining the crystal resonator at a constant temperature. In an OCXO, the crystal resonator is housed in a temperature-controlled chamber, commonly referred to as an "oven."

This oven maintains the crystal at a constant, optimal temperature, thereby minimizing the frequency variations that typically occur with temperature fluctuations. The result is an oscillator with excellent short-term and long-term stability, often achieving frequency stabilities in the parts-per-billion (ppb) range.

 

The anatomy of an OXCO. Image used courtesy of Lim and coauthors

 

OCXOs find applications in systems where timing accuracy is paramount. This includes telecommunications equipment, satellite navigation systems, radar installations, and precision test and measurement setups. 

 

The Challenge of Holdover Time

Holdover time is a critical parameter in the performance of Oven-Controlled Crystal Oscillators (OCXOs). It refers to the duration for which an oscillator can maintain a specified level of frequency accuracy when its primary reference clock is unavailable. 

In network systems, such as telecommunications and data centers, the primary time source might be a GPS signal or a network-based time protocol. When this primary reference is lost—due to equipment failure, environmental conditions, or other disruptions—the system switches to "holdover" mode, relying on the internal OCXO as its timing reference.

 

The Epoch Platform features 2x longer holdover times, which ensures reliable, continuous network operations. Image used courtesy of SiTime

 

The challenge lies in ensuring that the OCXO can maintain the required frequency stability for an extended period, often measured in hours. Traditional quartz-based OCXOs are sensitive to environmental factors like temperature fluctuations and airflow, which can degrade their performance over time. This is particularly problematic in applications like 5G networks, where even minor timing deviations can lead to data loss or network instability.

With all that in mind, achieving long holdover times under varying environmental conditions is a significant challenge, driving the need for advanced OCXO solutions that offer better resilience and stability.

 

Why This Matters

As the world moves towards more advanced and interconnected systems, the Epoch Platform may be poised as a key enabler in this evolution. Currently, engineering samples of the SiT58xx Epoch Platform are available for select customers with volume production expected in early 2024.