Electronic Design

Oscillators And Timing Devices

Low-Profile VCO Handles Demanding W-CDMA Applications
The SMV2330L surface-mount voltage controlled oscillator (VCO) is specially designed for quick integration into PLLs. With a low-profile package, this device generates frequencies between 2300 and 2360 MHz within a control-voltage range of 0.5 to 2.5 V dc. This allows the error voltage to be taken directly from the IC's charge pump circuitry.

Conserving energy, the VCO draws only 8 mA of current from a 2.7-V dc supply. Its 0.3- by 0.3- by 0.08-in. size saves valuable pc-board space. This device exhibits a spectral purity of −88 dBc/Hz. It is designed to function over an extended commercial temperature range of −30°C to 85°C. To minimize the pulling and pushing effect of the load on the VCO, it incorporates a 2-dB buffer pad. It pulls less than 13 MHz with a 14-dB return loss and pushes less than 10 MHz/V within a 5% change in the supply voltage.

According to the company, the SMV2330L is suited for automated surface-mount assembly and reflow. Also, it functions well for demanding W-CDMA basestation applications. It is available in tape-and-reel packaging for production requirements. The VCO costs $15.95 each for prototyping.

Z-Communications Inc., 9939 Via Pasar, San Diego, CA 92126; (858) 621-2700; fax (858) 621-2722; www.zcomm.com.

Surface-Mount VCXOs Provide Data Recovery In Harsh Environments
The T6020 and T6021 surface-mount voltage-controlled crystal oscillators extend wireless and data communications in harsh environments. They function over an extended temperature range of −40°C to 85°C. The VCXOs provide clock and data recovery in harsh environments.

Both models operate over the 3- to 45-MHz range. While the operating frequency is crystal stabilized, the output frequency can be pulled on either side of nominal. The T6020 offers a frequency pull of ±50 ppm, and the T6021 may be pulled ±75 ppm. The VCXO frequency can be locked on to the incoming data signal. A dc control voltage in the 0.5- to 4.5-V range produces the desired frequency pull. The control voltage at center frequency is 2.5 V. Both devices are compatible with CMOS logic. Startup time is less than 5 ms. At 5-V and 45-MHz operation, current draw is less than 25 mA.

According to the company, the T6020 and T6021 suit mobile electronics equipment, including cell phones, modems, and GPS units. The VCXOs are available in tape-and-reel packaging. The overall dimensions of the devices are 5 by 7 by 1.9 mm. In OEM quantities, the devices cost $16.50 each.

MF Electronics, 10 Commerce Dr., New Rochelle, NY 10801; (914) 576-6570; fax (914) 576-6204; www.mfelectronics.com.

TCXO Suits Next-Generation Mobile Communications Devices
The CFPT-9000 miniature temperature-compensated crystal oscillator (TCXO) offers up to Stratum 3 stability for SDH/Sonet telecommunications systems. According to the company, it meets the needs of next-generation mobile communications devices.

The TCXO is implemented using the company's Pluto fourth-order temperature-compensation ASIC. The Stratum 3 stability of ±0.28 ppm is possible for output frequencies up to 20 MHz over the 0°C to 50°C temperature range. Standard frequencies include 12.8, 13, 16.384, 16.8, and 19.44 MHz. Frequencies up to 40 MHz are available at lower stabilities. Wide operating temperatures can also be specified at stabilities from ±0.5 ppm. Linear frequency adjustment via an external control voltage is custom definable from ±5 to ±40 ppm. The CFPT-9000 operates from power supplies down to 2.4 V. It provides HCMOS or sinewave output with tristate option.

Prices range from $10 to $100, de-pending on quantity and specification.

C-MAC MicroTechnology, 4222 Emperor Blvd., Ste. 300, Durham, NC 27703; (919) 941-0430; fax (919) 941-0530; Internet: www.cmac.com.

Zero-Delay Clock Buffers Support PC133 DIMMs
A family of five zero-delay clock buffers supports PC133 dual in-line memory modules (DIMMs). The buffers are designed for high-speed motherboard applications, including those using 133-MHz SDRAM. They also function in applications requiring multiple low-skew clocks that are phase-matched to a reference clock, such as a memory module clock tree where parallel SDRAMs require identical clocks.

Suiting applications broader than DIMM or PCI bus clocking, the buffers meet the JEDEC open standards. All parts in the family operate at 3.3 V. They are spread spectrum-tolerant and feature a cycle-to-cycle jitter rate of ±75 ps. For DIMM applications, the FS612509-01 features nine outputs while the FS612510-01 features 10 outputs. Both operate at 133 MHz with a maximum output frequency of 140 MHz. They are available in 24-pin 4.4-mm TSSOP packages.

Meeting all of the above specifications, the FS612509-02 and FS612510-02 feature a power-down option that turns the PLL off and forces all outputs low when the reference clock stops. For PCI bus applications, the FS6108 drives up to eight PCI lines. It is optimized for 33-MHz operation and offers a maximum output of 66 MHz. It is available in a 16-pin 0.15-in. SOIC package.

The FS602509-01, FS612509-02, FS612510-01, and FS612510-02 buffers cost $1.43 each. The FS6108 costs $1.09/unit. All pricing is for orders of at least 10,000 per year.

AMI Semiconductor, 16644 W. Bernardo Dr., Ste. 301, San Diego, CA 92127; (858) 385-1808; fax (858) 385-1809; www.amis.com.

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