MEMS resonator and oscillator circuitry integrated onto single IC
The company’s Si50x CMEMS oscillators represent a “leap ahead of quartz-based timing devices with superior frequency stability, reliability and programmability” Silabs asserts. Designed to replace general-purpose crystal oscillators (XOs) in cost-sensitive, low-power and high-volume industrial, embedded and consumer electronics applications the oscillators are based on Silicon Labs’ patented CMEMS technology – the first to enable MEMS structures to be built directly on top of standard CMOS wafers in high-volume fabs, resulting in fully integrated, highly reliable monolithic “CMOS+MEMS” IC solutions. The company first fabricates the oscillator and frequency synthesiser circuitry, then planarises the wafer, deposits silicon on top, and fabricates the MEMS section in that silicon.
A single MEMS resonator reference frequency is used – 25 MHz – and the mode of resonance is in the plane of the silicon die – in this device, MEMS flexing is in the X/Y directions only, not along the Z axis. Temperature stability is enhanced by combining silicon and SiO2 patterns in the MEMS element; these material have opposing responses to changes in temperature and increase the inherent stability of the MEMS resonator’s frequency by passive compensation.
The oscillator family achieves smaller size, higher reliability, better aging and higher integration than existing frequency control solutions; Silabs adds that;
• CMEMS oscillators are manufactured in a high-volume CMOS fab with unified foundry lines that support wafer probing of complete oscillator systems for state-of-the-art quality and process control.
• 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.
• CMEMS 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 70C) and industrial (-40 to 85C) 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.
With the Si50x CMEMS oscillator family, you do not have supply chain problems that are typical for traditional quartz-based solutions, Silabs adds; because CMEMS oscillators are integrated, monolithic ICs, they are packaged in widely produced, moulded-compound 4-pin packages, again ensuring a predictable and reliable supply chain.
The Si50x oscillators are available for web-based customisation with short two week sample lead times or optionally available with “0-day” lead time via instantaneous field programming at the customer’s site by Silicon Labs’ sales channel partners. In addition, the Si50x oscillators are pin- and footprint-compatible with existing quartz or MEMS oscillators, enabling a quick, easy drop-in replacement solution.
The Si50x family includes four products that enable thousands of flexible timing configurations:
• 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
• Si504 fully programmable oscillator supporting all potential configuration features 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 Mike Petrowski, vice president and general manager of Silicon Labs’ timing products. “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.”
The CMEMS oscillators come in three industry-standard 4-pin DFN package sizes: 2 x 2.5 mm, 2.5 x 3.2 mm and 3.2 x 5 mm. Pricing begins at $0.44 (10,000). The Si501-2-3-4-EVB Evaluation Kit is priced at $99 and hosts a pre-programmed Si504 device and open sockets in each package size.
Silicon Labs; www.silabs.com/CMEMS
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