Thursday, February 12, 2009
MEMS oscillators harness electrostatic forces rather than relying on the piezoelectric effect used in traditional quartz crystals. But silicon resonators are less stable than quartz, forcing MEMS makers to include temperature compensation using a power-hungry phase-locked loop (PLL). By adding a piezoelectric thin-film atop its silicon resonator, and using a switched capacitor method for performing temperature compensation (instead of a PLL), the Swiss Center for Electronics (CSEM) is claiming a 1,000-fold decrease in power consumption in a paper presented this week during the International Solid-State Circuits Conference. CSEM's piezoelectric silicon resonator consumes 3 microamps while achieving a native accuracy for its real-time clock of 5 parts per million/degree Celsius compared to 15 to 30 PPM/degreeC for typical MEMS resonators that consumes 3 or more milliamps.
Posted by R. Colin Johnson at 7:29 AM