SiTime unveils new Super-TCXO platform for edge networks

SiTime has expanded its MEMS-based Super-TCXO family with the introduction of the Elite X platform. These Super-TCXOs are designed to solve timing challenges in edge networks such as data centers, 5G front haul, connected cars, and industrial IoT.

For these applications, the precision timing devices need to operate reliably in harsh environments, including extreme temperatures as well as thermal shock and vibration. The new Elite X Super-TCXO family said to offer 2× better stability and 30× higher reliability over quartz-based timing devices. It also offers 20× better phase noise under vibration to minimize call and/or link drops in high-vibration environments.

The Elite X Super-TCXO platform also offer a 0.2 ps/mV power supply noise rejection (PSNR). This helps reduce the bill of materials by eliminating the need for a dedicated LDO for the TXCO, said the company.

Key specs for the Elite X TCXOs include +/-10 ppb frequency stability, an operating temperature range of -40°C to 105°C, and +/-0.5 ppb/°C dF/dT (frequency slope). It also is resistant to thermal shock and airflow. It operates over any frequency from 1 to 60 MHz with up to six decimal places of accuracy.

A lot of electronics are moving into harsher environments, said Piyush Sevalia, executive vice president of marketing at SiTime. The 5G cell phone infrastructure is going up everywhere – such as electricity poles, sides of building, and stadiums, and sensors are being deploy everywhere, including underground, under bridges, and the same thing with automotive, he said.

When electronics are subjected to the forces of nature, it has to withstand shock, vibration, temperature changes, and other factors like airflow, which are causing significant issues in electronics, Sevalia added. “One of the things this impacts is the timing chip.”

In addition, as more data is transmitted the timing need is becoming much more important and a lot more complicated, and both 5G and edge networks are growing dramatically, contributing to the need for the timing device to offer higher reliability, faster speeds, lower latency, and lower power consumption, he said.

By 2025 one in three mobile connections will be 5G, Sevalia said. “There’ll be about 22 million autonomous vehicles out by that time frame and there’ll be about 40 times more edge data centers than today.

“If you look at these three big macro trends when connections go to 5G, we need 10 times better time synchronization compared to 4G and we also need 50× lower latency for ADAS, and with 40× more data centers we need five times better accuracy, so that synchronization can happen faster and more accurately.”

The new Elite X Super-TCXO family is designed to be a replacement for mini-OCXOs in edge networks. Compared to the first family of Elite devices, the Elite X offers a 10× improvement in stability at 10 ppb as well as 4× lower power. Sevalia said there is no other TCXO in the industry with a stability of 10 ppm and at that stability it can replace an OCXO.

OCXOs solve problems in terms of stability but they are not as reliable, they have very high power consumption, and they are large devices, he said. The TCXO offers lower power with better stability, a smaller size, and immunity to shock and vibration, he added.

OCXOs are susceptible to thermal shock because any time the temperature changes rapidly, which can happen when transmitting a lot of data, the stability degrades and the system loses lock, Sevalia explained. This is avoided with the new TCXO because it offers much faster temperature tracking, along with much lower power consumption, he said.

Sevalia said the single biggest criteria in all of these applications is that the temperature changes need to be tracked very carefully. The Elite technology provides +/-0.5-ppb/°C frequency over temperature slope. “What that does even in the presence of a rapidly changing temperature environment and in the presence of shock and vibration, we can maintain 130 ns of time accuracy between radios in the same vicinity in a 5G deployment, which provides better reliability and synchronization in these harsh environments,” he said.

Also important to the overall performance of the edge networks are specs around aging, warm-up time, and power consumption. Key specs include +/-0.5 ppb daily aging and 110 mW typical power consumption.

As equipment operates, the timing component in the device is also running, and so the stability will change slightly over time, said Sevalia. In applications like remote sensors, which are battery operated, they need to maintain up to 1 ms of time error for up to 30 days, and limit the daily aging at a lower power than an OCXO, he said.

These devices also provide a very precise time reference for ADAS applications, even when vehicles are driving through tunnels, parking garages or anywhere the network signals aren’t as strong. “It allows the car to continue to be on the same time reference as the network infrastructure even though it may have lost the signal in a tunnel or other weak network areas. When they come out of this environment they synchronize easily with the network so the automated driving function is not impacted,” he said.

Samples of the SiT5501 Elite X Super-TCXO, measuring 7 × 5 mm, are available now, with volume production scheduled for third quarter of 2022. SiTime also offers a broad range of TCXOs and OCXOs with a range of stability: Elite X (+/-10-20 ppb stability), Emerald (+/-5 ppb), and Elite (+/-50-500 ppb) for communications, networking, automotive, and industrial IoT applications.