Aaron Partridge

SiTime is now sampling our new generation of high-frequency differential oscillators, the SiT9121 and 9122. These are designed for high speed serial interfaces, such as SONET, that require high clock frequencies and waveforms with fantastically clean edges.

At the very highest data rates even slight noise in the transmit or receive clocks can degrade data fidelity. And because of this the cleanliness standards on these clocks are very tight. The primary spec is that the jitter integrated from 12 kHz to 20 MHz must be less than one picosecond (one trillionth of a second). SiTime has the only MEMS oscillators capable of meeting this spec. In fact, SiTime’s new oscillators beat this by a factor of two, delivering clocks with only a half-picosecond integrated jitter.

In quartz, oscillators that can beat a picosecond are often called “extremely low jitter”. The extremely is well deserved – it is a very low number. For example, in half a picosecond light travels only 150 microns in a vacuum. An electrical signal in a copper wire travels at about half the speed of light. Thus a clock signal traveling in a printed circuit board goes about 75 microns in a half picosecond. That is roughly the width of a human hair.

So think of what these oscillators are doing. They are producing electrical waves that travel out from their pins, across PC boards, and into application ICs. These waves move at half the speed of light while their edges are where they should be to the width of a human hair. Pretty amazing!

This autumn is the 100th anniversary of a huge milestone in aviation – the first US Transcontinental Flight. On September 17th 1911 Cal Rodgers lifted off in his Right Flyer from Sheepshead Bay near New York City. On November 5th he landed in Pasadena California near Los Angeles. It took him 69 stops, of which about a third were crashes. Cal believed he could do something that had never been done before and then he did it. Cal’s transcontinental flight was both astounding and unexpected, and few people thought he would make it. He survived storms, hard landings, and an engine explosion – and he founded a new industry.

What is the connection to SiTime? It is that new ideas do not evolve incrementally; they burst on the scene exponentially. It took only ten years to develop an airline industry after this heroic pilot crashed his way across the country. Initially airlines delivered the mail, then soon people.

And who were the losers? The railroads. Before the airlines trains dominated mail delivery and transportation. Who today has letters delivered by train? Who travels across the US by train?

Was this foreseen by the railroad companies? Did they invest in airlines to maintain their control of transportation markets?  No. The airlines were started by entrepreneurs driven to do something new, not by railroad execs.

When industries change the incumbents rarely generate the change, and even less often manage the change. This is the case with MEMS oscillators. The companies driving this are not the incumbent quartz oscillator companies. The MEMS oscillator companies are started and run by entrepreneurs driven to do something new.

Now there are some exceptions to the rule. IBM and HP are examples of companies that have prospered across technology changes. But for every company that bridges the change there are many that don’t. And so time will tell how it works out in this case. It is likely that a few wise quartz companies will find ways to stay in the game, but most will not.

This June we began sampling our Encore-based oscillators, and in just four months we have delivered thousands of parts and registered scores of design wins. This is the most interest in a new product family we have seen, and it is showing the highest-ever conversion rate from samples to design wins.

Encore is our newest technology platform. With Encore we can build oscillators with 40 dB lower phase noise, 20x better frequency accuracy, and 100x better short term stability. We can build XOs, TCXOs, VCXOs, DCXOs, and a bunch of special functions. For example, we are sampling SiT8208’s and 8209’s, the world’s only MEMS oscillators with sub-picosecond 12 kHz to 20 MHz integrated phase jitter; and we are sampling SiT5000, 5001, and 5002’s, the world’s only sub-ppm MEMS TCXOs. These parts don’t just squeak by with one picosecond integrated jitter or one ppm accuracy, they typically are delivering half that.

While these are the world’s only MEMS oscillators with these capabilities, their performance levels are also rare in the quartz field. Quartz oscillators with sub-picosecond integrated jitter are often advertised as “extremely low jitter”, and not everyone can build them. On the accuracy side, sub-ppm TCXOs are also rare, and not everyone can build them either.

How can we develop oscillators in just a couple of years that most quartz companies can’t develop after decades? I describe this in my last post, but here is another way to look at it: It is because our technology is based on modern semiconductors and is highly leveraged; while in comparison the quartz oscillator technology is specialized and far less leveraged. We design our products within software ecosystems we don’t have to write because others have come before us and already written and tested them. We build our parts in billion dollar fabs that we don’t need to own because we leverage the huge investments of semiconductor companies. We package and test our parts in standard IC packages with standard tooling in standardized factories that we don’t need to build because we leverage a standard IC production infrastructure.

None of this works for the quartz guys. When they need to design new parts they don’t have an industrial design infrastructure supporting them but are mostly on their own. When they need to build their quartz blanks they must build their own specialized fabs. When they need to package and test their parts they must buy specialized equipment for their own specialized facilities. This takes time, soaks up capital, and hinders innovation.

The net result is that we innovate faster and push our technology further that the quartz incumbents. We move in strides in an industry where progress has been measured in steps.

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