Single die MEMS oscillator hits the mainstream
Silicon Labs has ported the low temperature MEMS technology it acquired with startup Silicon Clocks in 2010 to Chinese foundry SMIC. This allows a SiGe structure to be built on top of the passivation layer of a CMOS logic chip using the existing CMOS production line and eliminates the drift problems of dual die devices as the materials are specifically chosen to counteract thermal drift.
The programmable oscillators run up to 100MHz with frequency stability down to 20ppm and are aimed at cost-sensitive, low-power and high-volume industrial, embedded and consumer electronics applications such as digital cameras, storage and memory, ATM machines, point-of-sale equipment and multi-function printers. Higher speed devices are planned, says Mike Petrowski, vice president and general manager of Silicon Labs’ timing products.
The CMOS MEMS (CMEMS) technology enables guaranteed data sheet performance with 10 years of frequency stability including solder shift, load pulling, VDD variation, operating temperature range, vibration and shock. This guaranteed operating life performance is 10 times longer than typically offered by comparable crystal and MEMS oscillators. The oscillators tightly couple the MEMS resonator with CMOS temperature sensor and compensation circuitry, ensuring a highly stable frequency output in the face of thermal transients and over the full industrial temperature range. The end result is a predictable, reliable frequency reference over the long operating lifespans of industrial and embedded applications.
The Si50x CMEMS oscillators support any frequency between 32 kHz and 100 MHz. Frequency stability options include ±20, ±30 and ±50 ppm across 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 functionality.
Using CMOS MEMS rather than a crystal frees customers from supply chain problems that are typical for traditional quartz-based solutions. Because CMEMS oscillators are integrated, monolithic ICs, they are packaged in widely produced, molded-compound 4-pin packages, again ensuring a predictable and reliable supply chain. Devices can be programmed with a specific frequency at the bench, with the tool generating a dedicated part number that can be used for procurement, programmed in the factory before shipment. The Si50x oscillators are also pin- and footprint-compatible with existing quartz or MEMS oscillators, enabling a quick, easy drop-in replacement solution.
“The timing market has reached an inflection point in which the latest-generation MEMS-based oscillators are capable of providing reliable, cost-effective replacements for traditional crystal oscillators,” said Jeremie Bouchaud, director and senior principal analyst for MEMS and Sensors at IHS. “Silicon Labs’ CMEMS technology provides the most integrated crystal replacement solution to date by combining the MEMS resonator and frequency control circuitry into a single-die device optimized for high-volume electronic system designs.”
The Si50x family includes four products: the Si501 single-frequency oscillator with output-enable (OE) functionality; Si502 dual-frequency oscillator with OE and frequency-select (FS) functionality; Si503 quad-frequency oscillator with FS technology; and Si504 fully programmable oscillator with a 1-pin interface for fine-tuned frequency adjustments measured in parts per billion
“The Si50x CMEMS oscillator family introduces an important technological step forward in the frequency control market, combining all the manufacturing advantages of a single-die MEMS-based solution while retaining some of the best characteristics of general-purpose crystal oscillators and improving on both reliability and lead times,” said Petrowski. “By leveraging Silicon Labs’ expertise in MEMS design, device and process integration and mixed-signal technology, the Si50x family provides a best-in-class general-purpose oscillator solution for cost- and power-constrained embedded, industrial and consumer electronics applications.”
Production quantities of Silicon Labs’ Si501/2/3/4 CMEMS oscillators are available now in three industry-standard 4-pin DFN package sizes: 2 mm x 2.5 mm, 2.5 mm x 3.2 mm and 3.2 mm x 5 mm. Pricing for Si50x oscillators in 10,000-unit quantities begins at $0.44. For evaluation and application development, Silicon Labs offers the Si501-2-3-4-EVB Evaluation Kit priced at $99, featuring a pre-programmed Si504 device and open sockets in each package size for customer evaluation.
www.silabs.com
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