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High-frequency crystal oscillators provide low jitter, save board space

Sunnyvale, Calif. — Maxim Integrated Products has introduced the DS4-XO series of crystal oscillators that support frequency operation from 75 MHz to 622.08 MHz. These miniature crystal oscillators are available in a 5 x 3.2-mm package and provide jitter performance of less than 1 ps RMS (12 kHz to 20 MHz) over the -40°C to +85°C extended temperature range.

Manufactured using fundamental AT-cut crystal technology with no overtone, the DS4-XO series integrates a low-noise PLL-based oscillator designed in Maxim's own SiGe process. Touted as fifty-five percent smaller than competitive solutions, the DS4-XO series targets space-constrained designs used in Fibre Channel, Ethernet, 10G Ethernet, SONET/SDH, InfiniBand, GPON, BPON, PCI Express, and SAS/SATA applications.

The DS4-XO series' miniature package incorporates thermally managed design techniques specifically targeted for high-current (65 mA to 75 mA, typ), high-frequency (100 MHz and greater), differential-output (LVDS, LVPECL, HCSL) applications. LVDS and LVPECL output options are available for all frequencies except the 100-MHz version. This frequency is generally used in PCI Express applications and is provided with a (differential) HCSL output type, said Maxim.

These crystal oscillators compete with SAW-based oscillator designs, offering comparable phase-jitter performance of <1 ps RMS. The DS4-XO devices are said to deliver a much higher degree of frequency stability (±40 ppm versus ±100 ppm or greater) over the extended temperature range, as compared to the SAW-based types. In addition, the DS4-XO series provides extremely low ±7 ppm aging over 10 years, compared to SAW-based oscillators that typically provide ±1 ppm aging per year, said Maxim.

Unlike third-overtone oscillator designs, the DS4-XO oscillators integrate a LC-PLL circuit that uses fundamental AT-cut crystals; therefore, they completely eliminate the spurious modes of operation that result in extreme frequency deviation, said Maxim. In addition, the PLL-based design accommodates operating frequencies up to 622.08 MHz and higher, if desired.

In contrast, third-overtone designs provide limited frequency operation with maximum frequencies of approximately 200 MHz, said Maxim. The standard frequencies for the DS4-XO series of crystal oscillators are: 77.76 (DS4776), 106.25 (DS4106), 125 (DS4125), 155.52 (DS4155), 156.25 (DS4156), 160 (DS4160), 212.50 (DS4212), 311.04 (DS4311), 312.50 (DS4312), 425 (DS4425), and 622.08 MHz (DS4622).

The DS4-XO crystal oscillators integrate a thermal pad that ensures the safe operation of the crystal element over the entire extended temperature range and also enables high-current applications. These devices are available in a 5.0 x 3.2 x 1.49 mm, 10-pin, LCCC surface-mount ceramic package.

Pricing: Starts at $7.39 (1000-up, FOB USA).
Availability: Samples are available.
Datasheets: DS4776 and
DS4106

Maxim Integrated Products , 1-800-998-8800, www.maxim-ic.com

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