Silicon Labs has developed a new low-drift, single-die MEMS oscillator fabricated using a CMOS process. By porting low-temperature MEMS technology to the SMIC foundry, they managed to build a SiGe structure on top of the passivation layer of a CMOS logic chip using an existing CMOS production line. The drift problems of dual-die devices are eliminated by selecting specific materials to counteract thermal drift. The programmable oscillators operate at up to 100 MHz with frequency stability down to 20 ppm. Higher speed devices are planned, according to a Silicon Labs’ source.
CMOS MEMS (CMEMS) technology allows data sheet performance for frequency stability to be guaranteed for ten years, including solder shift, load pulling, supply voltage variation, operating temperature range, vibration and shock. This is ten times longer than typically offered by comparable crystal and MEMS oscillators. The oscillators tightly couple the MEMS resonator with CMOS temperature sensing and compensation circuitry, ensuring a highly stable frequency output despite thermal transients and over the full industrial temperature range.
Si50x CMEMS oscillators support any frequency from 32 kHz to 100 MHz. Frequency stability options include ±20, ±30 and ±50 ppm over extended commercial (-20 to +70°C) and industrial (-40 to +85°C) operating temperature ranges. The CMEMS oscillators also offer extensive field- and factory-programmable features, including low-power and low-period jitter modes, programmable rise/fall times, and polarity-configurable output enable.