SUNNYVALE, Calif.—The dream of integrating a high-precision oscillator on a standard CMOS chip has been realized by Silicon Laboratories Inc. and its new Si50x family of CMEMS oscillators.
Conceived by Silicon Clocks, which was acquired in 2010, Silicon Labs has since been quietly perfecting its single-die solution that allows MEMS oscillators to be fabricated atop a CMOS chip in any standard foundry. As a result, mixed-signal chip maker Silicon Labs now lays claim to the world's first single-die alternative to quartz crystals.
"CMEMS oscillators match the best characteristics of quartz crystals while increasing stability, improving reliability and shortening lead times," said Mike Petrowski, vice president and general manager of Silicon Labs' timing products. "We believe CMEMS is now the best-in-class general-purpose oscillator solution for cost- and power-constrained embedded, industrial and consumer electronics applications."
By casting a micro-electro-mechanical system oscillator (yellow) atop a standard CMOS chip, CMEMS marries the scalability and economy of silicon to the reliability and stability of MEMS.
Source: Silicon Labs
Silicon Labs' CMEMS technology, of which the Si50x is the first family, combines a MEMS resonator atop its frequency control circuitry on a single CMOS die, enabling standard foundries to produce the CMEMS oscillators on their high-volume fabrication lines. Silicon Labs is targeting its CMEMS oscillators at mass market applications including digital cameras, storage and memory devices, ATM machines, point-of-sale equipment and multi-function printers.
To guarantee supplies, CMEMS oscillators are currently fabricated on the massive line at Semiconductor Manufacturing International Corporation (SMIC)--the same Chinese foundry used by Broadcom, Qualcomm and Texas Instruments.
SiTime mentioned above is selling oscillators that can be embedded in the same package as the microcontroller. I would say that's the way to go.
I wonder how SiLabs compares to the competition? Personally, I tend to favor MEMS platforms based on SOI that are DRIE:d into the structures. Mostly due to the simplicity and the use of monocrystalline Si. SiLabs deposit a pretty thick layer of poly-SiGe (SiGe can be deposited at pretty low temperatures which is critical if CMOS-wafers are the substrate that is deposited) that is formed into the resonator structure.
Guess in the end it's a question about the yield of the processes.
The 2mm x 2.5mm size is nice. It's disappointing how large a lot of the current oscillators are compared to the tiny chips around them. Sometimes the oscillator is bigger than the MCU.
My next question is, when can I get these integrated with the MCU on the same dice?
David Patterson, known for his pioneering research that led to RAID, clusters and more, is part of a team at UC Berkeley that recently made its RISC-V processor architecture an open source hardware offering. We talk with Patterson and one of his colleagues behind the effort about the opportunities they see, what new kinds of designs they hope to enable and what it means for today’s commercial processor giants such as Intel, ARM and Imagination Technologies.