Replacing well-established technology is always a tricky proposition. Researchers have been trying to displace quartz crystals with Micro-Electromechanical system (MEMS) resonators for more than 40 years. Based on a new wafer encapsulation approach, SiTime Corp. may finally have a viable solution. The company’s MEMS-First wafer-level encapsulation and packaging technology addresses the stability and low cost required for high-frequency oscillator applications.
Built in epitaxially sealed epipoly (epitaxially grown polysilicon) chambers buried under the wafer surface, the MEMS resonator structure is isolated from external contamination prior to packaging. A vacuum of approximately 10 mT seals out water and other high- vapor pressure contaminants at the wafer level. After dicing, the resonators are molded into standard plastic IC packages.
Testing showed a total frequency error of less than 100 ppb under a measurement noise floor of 200 ppb and a specified measurement error of 30 ppb. Measurements were made of the compensated frequency stability for the resonator in a plastic molded package as it was swept twice from 40 to +85C and back to 40C. The hysteresis was less than about 50 ppb. Over a one year timeframe, the MEMS resonator drifts less than 1ppm compared to typical small quartz crystals that drift 3- to 5ppm.
Specified in the frequency range of 1- to 125 MHz, initial production fixed frequency and programmable oscillators have a frequency tolerance of ±50 to ±100 ppm and aging of ±2ppm/year. The units are specified at ±150 psec of peak to peak jitter. Four-pin QFN type packaging options for the MEMS resonators include: 2.0 × 2.5 × 0.85 mm, 2.5 × 3.2 × 0.85 mm, 3.2 × 5.0 × 0.85 mm, and 5.0 × 7.0 × 0.85 mm packages.
For more information on SiTime oscillators, go to http://rbi.ims.ims.ca/4928-504.
Fabricating the MEMS mechanical resonator in a standard CMOS process allows the integration of additional circuitry on the surface to provide further system cost reduction and improved performance.
If you see a hitchhiker along the road in Canada this summer, it may not be human. That’s because a robot is thumbing its way across our neighbor to the north as part of a collaborative research project by several Canadian universities.
Stanford University researchers have found a way to realize what’s been called the “Holy Grail” of battery-design research -- designing a pure lithium anode for lithium-based batteries. The design has great potential to provide unprecedented efficiency and performance in lithium-based batteries that could substantially drive down the cost of electric vehicles and solve the charging problems associated with smartphones.
Robots in films during the 2000s hit the big time; no longer are they the sidekicks of nerdy character actors. Robots we see on the big screen in recent years include Nicole Kidman, Arnold Schwarzenegger, and Eddie Murphy. Top star of the era, Will Smith, takes a spin as a robot investigator in I, Robot. Robots (or androids or cyborgs) are fully mainstream in the 2000s.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.