SiTime improves automotive oscillators

To enable higher safety for advanced driver assistance systems (ADAS), infotainment and car-to-home wireless connectivity, SiTime Corp. has launched its latest generation of automotive oscillators with high stability and jitter performance. The AEC-Q100 SiT1623/25 automotive-grade oscillators, based on silicon MEMS technology, are designed to operate in extreme conditions, including high or low temperatures, high shock and vibration and harsh environments.

The low-power, low-jitter oscillator family for automotive offers two times better performance for the next generation of ADAS and infotainment, said Piyush Sevalia, SiTime’s executive VP, marketing.

SiTime’s focus is on solving the toughest timing problems, which the company calls precision timing, to ensure that the next generation of intelligent connected electronics will work, he said. “We deliver a clock signal that is precise, reliable and always works under any environment and that is how we define precision timing.

“In the electronics domain everything is becoming more intelligent and more connected,” Sevalia added. “When you get into this new realm where it’s all about intelligence and connectivity – higher speeds, more processing power and deployment in outdoor environments, you start running into issues with the traditional timing products and that’s where precision timing comes in.”

SiTime’s precision timing devices offer a range of benefits from low phase noise, low phase jitter and low power to lower aging, lower g-sensitivity, higher reliability and smaller size.

The company estimates that vehicles have up to 60 timing chips today and will reach 100+ chips by 2026, driven by compute, power and connectivity requirements for automotive electronics.

Precision timing is the heartbeat of all intelligent, connected automotive electronics, said Sevalia, and the number of timing chips in cars has grown and will continue to grow. In 2018, vehicles used up to 20 timing chips, at a price of $5-$8, and today they have about 35 to 60 timing chips because of the electronics added to the car, at a cost of $25-$35 per car, he added.

There will be more than 125 timing chips, priced at $50-$70 per car, by 2026, as the automotive industry gets to ADAS Level 4, which will require more electronics, more sensing and more connectivity in the network to ensure split-second decisions when in fully automated mode, Sevalia said.

In addition, the increasing demand for high-frequency connectivity will drive growth of silicon-based oscillators thanks to their inherent reliability, according to Yole Intelligence, part of Yole Group. The market research firm expects the MEMS timing industry to grow with a compound annual growth rate of 35% over 2021 to 2027.

The number of timing chips is rising in vehicles with increased electronics content and new applications such as V2X communication and electric vehicle powertrains. (Source: SiTime Corp.)

Core technologies

In 2013, SiTime “made a hard left turn” in product development to ensure that it was delivering value to the customer. The first new product under the new strategy was a device that was 80% smaller than any competing device, enabling a lot of traction in the mobile and IoT segments, said Sevalia.

“Since then, we’ve constantly introduced new products where the value is superior to quartz because we believe that is the only way that customers are going to use these devices,” he added. “Whether it is phase noise, jitter, stability, shock/vibration or size, those are the things we differentiate on and now we compete with quartz on supply chain issues.”

Sevalia attributes the company’s supply-chain success to SiTime’s three in-house core technologies – silicon MEMS, programmable analog and systems. Over the past 15 years, frequency stability and jitter performance has improved by 10,000× and 1,000×, respectively.

With all three core technologies in-house, the devices can be optimized, Sevalia said. “For example, if we can’t do something in the MEMS, we’ll put that burden on the analog and the systems and that is a very iterative and close-knit process that happens all the time inside the company.”

As a result, “we can innovate faster, which is evidenced by that 10,000× jitter improvement and other improvements, and secondly, we can provide a more compelling product to the customer. We believe we can do a lot more things in terms of features and performance that quartz companies cannot.”

SiTime also offers programmability through a base number of MEMS die (nine) and analog die (19) and 22 packages. These devices can be configured for a range of specifications, including frequency, stability, rise and fall times, voltage and temperature as well as output type and spread spectrum.

SiT1623/25 oscillators

Automotive applications require high-speed, in-car connectivity to transfer data between sensors, displays and central computers in the car. Each application has stringent jitter requirements to ensure reliable ADAS system performance.

The SiT1623/25 oscillators provide a high-temperature, low-power timing reference for automotive connectivity protocols, including SerDes and automotive Ethernet. They claim exceptional jitter performance, 500 and 750 fs RMS jitter for the SiT1625 and SiT1623, respectively.

Sevalia said excellent jitter and stability over an extended temperature range is important for ADAS performance.

“The focus of these new devices is jitter, which is 50% lower than previous generations, power consumption, which is 50% lower, and robustness in harsh environments,” he said. “Because data is moving faster through the system, you need better jitter. Our previous devices were around 1.5 ps and this device is 500 fs, which is a dramatic improvement.”

The SiT1623/25 oscillators offer 50% lower jitter and power consumption. (Source: SiTime Corp.)

In addition, the oscillators have to work in heavy vibration and heavy shock environments with extreme temperatures, he added. “The devices have a frequency stability of +/-50 ppm over a temperature range of -40°C to 125°C, which is about 2× better than quartz-based competitors.”

In addition to the +/- 50-ppm frequency stability, the family is offered at +/- 30 ppm over an operating temperature range of -40°C to 105°C.

These automotive oscillators offer several frequency options. The SiT1623 supports nine commonly used frequencies between 8 MHz and 50 MHz, while the SiT1625 supports 12 commonly used frequencies between 8 MHz and 100 MHz. Both devices offer supply voltages of 1.5 V, 1.8 V, 2.5 V and 3.3 V, well suited for automotive applications.

The oscillators also offer low power consumption. The SiT1623 consumes 1.8 mA typical at 1.8 V, while the SiT1625 uses 2.3 mA typical at 1.8 V. Both offer 1-μA standby current and provide a LVCMOS-compatible output.

These devices can be used in a range of automotive applications. These include ADAS, domain controller, digital cockpit, infotainment, cameras, and driver monitoring systems.

The SiT1623/25 devices are available in several package sizes: 1.6 × 1.2 mm, 2.0 × 1.6 mm, 2.5 × 2.0 mm and 3.2 × 2.5 mm. They are RoHS and REACH compliant, lead-free, halogen-free and antimony-free.

Engineering samples are available now for qualified customers, followed by general sampling in July 2023. Volume production is expected in early 2024.