Wireless infrastructure timing solved

There’s a huge precision timing opportunity based on today’s higher system density and complexity. Precision timing, especially addressing application segments such as electric vehicles/advanced driver assistance systems (EV/ADAS), 5G, IoT, mobile, and the cloud. SiTime Corp.’s new precision timing platform, Elite RF, not only simplifies the timing architecture in the wireless infrastructure, but the Elite RF Super-TCXO also delivers higher bandwidth and lower latency — critical factors for 5G and satellite communications.

Timing, while extremely important, is surprisingly still often ignored. Mini-OCXOs represented the primary timing reference for 5G and SATCOM radios, mainly because they delivered stability over changing temperature to clock advanced synchronized radios. They represented the go-to solution even with their downside; while accurate, they are also unreliable especially in harsh conditions. They also consume excessive power and board space and require additional components such as jitter cleaners and VCXOs to generate RF-capable clocks. Just one Elite RF Super-TCXO eliminates the additional components, according to SiTime.

The SiT5376 precision MEMS Super-TCXO is engineered for a combination of environmental resilience, low phase noise, low power, and compact size, making it suited for precision timing in RF systems. Leveraging SiTime’s unique DualMEMS and TurboCompensation temperature sensing technology, the SiT5376 delivers stable timing in the presence of environmental stressors such as airflow, temperature perturbation, vibration, shock, and electromagnetic interference (EMI). It can be factory-programmed to any combination of frequency, voltage, and pull range.

Figure 1: SiTime’s SiT5376 wireless infrastructure timing solution versus a quartz OCXO (Source: SiTime)

It was one thing to use the mini-OCXOs when the number of devices used was low. Now, however, timing requirements are more stringent, and the number of timing chips necessary have dramatically increased beyond their quartz-based capabilities. As devices continue to shrink, integration challenges abound.

For example, in 2018, 20 timing chips were used in EV/ADAS automotive applications with a cost of $5 to $8/car. In 2022, the number grew to 35-50 chips at a cost of $25 to $35/car and by 2026 the forecast is 125+ timing chips with a price of $50 to $70/car.

The IoT and mobile opportunity rests on ever-smaller footprints and a 10-year battery life requirement and for 5G, it requires 10× better timing in 10×  more radios, as well as 10× more bandwidth at 1/40^th the latency. For 4G, the cost of quartz timing per radio is $10 to $15, and for 5G, pricing ranges from $20 to $30 for timing devices per radio.

Purpose-built to withstand extreme 5G environments, the Elite RF wireless infrastructure timing solution delivers improved phase noise, accuracy, and resilience in a single, highly integrated device that meets the IEEE 1588v2 timing synchronization protocol.

SiTime estimates that the new platform will expand its serviceable addressable market by approximately $150 million as the company addresses target applications such as infrastructure radios in small cells, remote radio units (RRUs), microwave backhaul, and SATCOM equipment.

Key features of the Elite RF Super-TCXO family include a 60- to 220-MHz frequency range, ±100 ppb stability over temperature, an operating temperature range of -40 °C to +105 °C, and ±0.9 ppb/°C stability over temperature slope. The family also delivers ±400 ppm digital control with ±0.05 ppt (parts per trillion) resolution, 100 fs typical integrated phase jitter (19.2 MHz, 12 kHz to 20 MHz integration range), and 144 mW power consumption at 1.8 V.

Benefits of the SiTime MEMS Elite Platform TCXOs for 5G include 50× quality, 30×  reliability and 20×  mechanical shock resistance improvements,  as well as 10× better frequency stability with rapid thermal gradients, along with excellent power supply noise rejection, said SiTime.

Designing an Elite Platform TCXO into 5G equipment allows one radio design to be used globally, cutting development time and speeding time to market, said Piyush Sevalia, executive VP of marketing, SiTime.

In the past, silicon was historically the winner in processing, storage, power, and timing, said Sevalia. Now, however, the Elite RF MEMS TCXO is winning in timing given its higher performance, lower power, small size, programmability, stability, high reliability and the ability to handle harsh environments including shock and vibration challenges, he added.

Housed in a 5.0 × 3.5-mm ceramic package, the SiT5376 is available for limited customer sampling with general sampling to follow in the second quarter of 2023. Mass production is expected in the third quarter of 2023.