editor's blog
Subscribe Now

Comparing Oscillator Temp Compensation

MEMS oscillators are making a serious challenge to quartz these days. We looked at Sand 9’s approach recently, but as I thumbed back through other recent announcements, I came back across one that, in retrospect, had some relevant bits to discuss.

Silicon Labs’ earlier announcement focused on the CMOS+MEMS aspect of their work. At the time, I didn’t see anything I could add to the discussion, so I let the announcement stand on its own. But in light of some of the issues I covered in Sand 9’s release, I thought there were some things to come back to on the Silicon Labs story – some of which weren’t immediately apparent in their release.

This relates to temperature compensation, which seems to be the number one concern with these devices. Yes, everyone tries to compensate with circuitry, but if you can minimize the raw temperature effects, then the compensation is easier.

We looked at the stack that Sand 9 built to do this – silicon and oxide having opposing temperature coefficients and therefore physically compensating for each other. Well, Silicon Labs does something similar but not identical.

They use SiGe as the active material for the resonator, but they back it with SiO2, which again opposes the temperature characteristics of the SiGe.

The other subtlety here relates to the CMOS processing aspect, although again, it seems to be two different ways of accomplishing the same thing. Sand 9 discussed how having the compensation ASIC in the same package was important so that the ASIC was experiencing the same temperature as the sensor it was compensating.

With the Silicon Labs approach, this happens as a direct result of combining MEMS and CMOS on the same die: The compensation circuitry isn’t just next to the sensor; it’s on the same die as the sensor. So again, it experiences the same temperatures as the sensor. It’s probably even closer, although at some point, if you start arguing about hot spots on the actual die, you could question whether mere monolithic integration guarantees better compensation. It depends on where things are on the die and how “hot” the circuits are. So it remains to be proven whether monolithic compensation is practically any more effective than a well-engineered die-by-die solution.

You can find more on Silicon Labs’ process here.

Leave a Reply

featured blogs
Jan 17, 2020
[From the last episode: We saw how virtual memory helps resolve the differences between where a compiler thinks things will go in memory and the real memories in a real system.] We'€™ve talked a lot about memory '€“ different kinds of memory, cache memory, heap memory, vi...
Jan 16, 2020
While Samtec started as a connector company with a focus on two-piece, pin-and-socket board stacking systems, High-Speed Board Stacking connectors and High-Speed Cable Assemblies now make up a significant portion of our sales. To support development in this area, in December ...
Jan 16, 2020
Betting on Hydrogen-Powered Cars On-demand DRC within P&R cuts closure time in half for MaxLinear Functional Safety Verification For AV SoC Designs Accelerated With Advanced Tools Automating the pain out of clock domain crossing verification Mentor unpacks LVS and LVL iss...
Jan 16, 2020
This little robot arm continually points to the current location of the International Space Station (ISS)....

Featured Video

RedFit IDC SKEDD Connector

Sponsored by Wurth Electronics and Mouser Electronics

Why attach a header connector to your PCB when you really don’t need one? If you’re plugging a ribbon cable into your board, particularly for a limited-use function such as provisioning, diagnostics, or testing, it can be costly and clunky to add a header connector to your BOM, and introduce yet another component to pick and place. Wouldn’t it be great if you could plug directly into your board with no connector required on the PCB side? In this episode of Chalk Talk, Amelia Dalton chats with Ben Arden from Wurth Electronics about Redfit, a slick new connector solution that plugs directly into standard via holes on your PCB.

Click here for more information about Wurth Electronics REDFIT IDC SKEDD Connector