A real-time clock oscillator unveiled by Epson Toyocom Corp. is said to require 70 percent less board space while occupying 75 percent less volume that its predecessor. The new real-time oscillator (SG-3050BC) uses Epson's proprietary QMEMS process to squeeze all functions into a 2.2- by 1.4- by 1-mm package. The 32.768-KHz crystal oscillator is claimed to be the smallest currently available.
BOTTOM LINE: QMEMS uses the same sort of photolithography, etching, metallization and sacrificial-layer removal steps as silicon MEMS chips, just with the quartz material. Consequently, their size is now rivaling the smallest MEMS oscillator chips. The MEMS makers say that QMEMS is not "real" MEMS, and the Epson says that silicon is less stable than quartz. One thing that QMEMS cannot do is be integrated with silicon chips the way Silicon Clocks allows its IP to be licensed by CMOS chip makers. In the end, the choice of MEMS or QMEMS will be best determined by the application engineer.
