Battered in recent years by the depressed telecom market, oscillator manufacturers are diversifying their product portfolios to target opportunities in Bluetooth and wireless-LAN markets, where tighter stability, lower power consumption and smaller package sizes are critical to customers.
Although 802.11b is the primary standard for WLAN applications, the newer, higher-data-rate 802.11a and 802.11g standards are driving frequency control requirements for tighter stability and smaller packages. Standard frequencies for WLAN applications are 22 MHz, 40 MHz and 44 MHz.
Key products that embed Wi-Fi functionality include handheld and mobile PCs and mobile-phone handsets. Bluetooth applications include mobile handsets and headsets as well as PDAs.
"We definitely see a big boon in Wi-Fi," said Roger Burns, western region engineering sales manager at Fox Electronics (Fort Myers, Fla.). The introduction of combo 802.11a/g chip sets is driving clock oscillator requirements, Burns said. "Wi-Fi specs have moved from [a frequency stability of] 25 ppm for the 802.11b version to 20 ppm for 802.11a/g, so we've tightened the stability," he said. "And, depending on what the end user is building, they've moved to smaller packaging, such as 5 x 3.2 mm." Burns added, however, that customers continue to use the 7.5 x 5-mm package whenever possible because of its low cost (less than 50 cents).
In portable, handheld and wireless markets, where size matters, Fox earlier this month introduced the FOX923E temperature-compensated voltage-controlled crystal oscillator (TCVCXO). The part comes in a 3.2 x 2.5 x 1.2-mm package, which is half the length of the package used for Fox's previous oscillator family. The new part's frequency stability is plus/minus 2.5 ppm over the standard operating temperature range (-20 degrees C to 75 degrees C) and plus/minus 0.2 ppm over the supply voltage range of 3.0 volts plus/minus 5 percent. Prices start at $1.99 each in 10,000-piece quantities for a part with a stability of plus/minus 2.5 ppm and a frequency of 26 MHz. Delivery is eight weeks.
Fox also offers the F330 series of oscillators in a 3.2 x 5 x 1.2-mm package with frequency stabilities of plus/minus 100, plus/minus 50, plus/minus 25 and plus/minus 20 ppm in frequency ranges from 1.8 Hz to 50 MHz. The devices target use in handheld, portable and wireless applications.
With an eye on similar applications, Fox launched a family of VCXOs in a 5 x 3.2-mm package earlier this year. The FVS25AXT is a 3.3-V low-profile VCXO with a frequency range of 2 to 50 MHz and a frequency stability of plus/minus 50 ppm.
Taro Hishinuma, product manager for AVX Corp. (Myrtle Beach, S.C.) agreed that one of the biggest trends in the wireless-LAN market is miniaturization. WLAN adoption in the laptop is driving miniaturization, he said. Demand will grow for package sizes of 3.2 x 2.5 or 2 mm over the next two to three years, Hishinuma predicted, and frequency tolerances will tighten as requirements change.
Targeting demand for WLAN applications, AVX's K30 clock oscillator features a low-profile ceramic package for portable electronics such as digital cameras, notebook PCs, PDAs and 802.11 wireless-networking systems. Available in a 5 x 3.2-mm ceramic package, the K30 series offers a frequency range from 8 MHz to 67 MHz with a stability of plus/minus 25 ppm. The company plans to add a tighter-tolerance, 20-ppm part to the family.
Typical unit pricing for the K30 is less than $1 in quantities from 1,000 to 5,000, depending on frequency and tolerance. Delivery is eight to 10 weeks. Samples of popular frequencies ship off-the-shelf.
Similarly, Raltron Electronics Corp. (Miami) expects crystal and oscillator packages to continue to shrink. By year's end, the company will offer crystal units in 2.5 x 2-mm and 2.5 x 1.6-mm packages and clock oscillators in 4 x 2.5-mm and 3.2 x 2.5-mm packages. Designed for WLAN and portable applications, Raltron's COM23 surface-mount oscillators, introduced in April, feature WLAN standard frequencies of 22, 40 and 44 MHz in a 5 x 3.2 x 1.3-mm ceramic package. Frequency stabilities range from plus/minus 25 ppm to plus/minus 100 ppm; aging is plus/minus 3 ppm per year. Standard frequencies range from 2.5 MHz to about 66.67 MHz. The standard temperature range is -10 degrees C to -70 degrees C; a wider range, -40 degrees C to 85 degrees C, is also available.
SaRonix LLC (Menlo Park, Calif.) cites a demand for lower power consumption in addition to smaller packaging and tighter stability. Notebook computers are among the products driving that requirement in the wireless segment, according to Brandon Ogilvie, marketing and E-Business Group manager at SaRonix.
Over the past two years, SaRonix has supported 802.11 WLAN technology in the 40- and 44-MHz range with devices in 5 x 7-mm package sizes. Now the company is rolling parts of comparable performance that measure 3 x 5 mm.
"It's been a major technical challenge to preserve performance while going through such a dramatic size reduction," said chief technical officer Craig Taylor. "We're offering the new devices at 3.3 V and lower voltages to help save battery power and extend battery life, which is preferred among the end-user base."
The S1633 (3.3-V) and S1634 (2.5-V) crystal clock oscillators are available for sampling and prototyping. Key specs include a frequency range of 40 MHz to 60 MHz, frequency stability of plus/minus 25 ppm and plus/minus 50 ppm, and an operating range of -20 degrees C to 70 degrees C. Both devices come in a 3.2 x 5 x 1.3-mm package. In addition to 802.11 applications, the oscillators can be used in notebooks and palmtops, PCs, PCMCIA cards and other portable apps.
SaRonix has also introduced a temperature-compensated crystal oscillator in a 5 x 7-mm surface-mount ceramic package that targets microwave wireless digital data link applications. The S6C series TCXO, with a voltage control option, is tailored for microwave and wireless networking, digital data links, GPS/navigation and commercial satellite comms applications. The part offers a clipped-sine output from 10 MHz to 30 MHz. The company said the TCXO requires only a 2-mA input from a 3-V supply to produce frequency stability as tight as plus/minus 1 ppm over the temperature range (0 to 50 degrees C). Phase noise is less than -110 dBc/Hz at 100-Hz offset (-140 dBc/Hz at 10-kHz offset).
The S6C "offers extremely good phase noise performance, required for wireless digital data links," Taylor said. "We've used a much more precise mechanism for adjusting frequency output to compensate for the effect of temperature on frequency."
Oscillator manufacturers also report an uptick in the cell phone business-yet another design slot that drives requirements for smaller packaging. The cell phone market is reviving as the 3G multifunction cell phone business picks up, said Mike Walczak, president of NDK America Inc. (Schaumburg, Ill.). He expects to see more TCXOs and tighter-tolerance devices used in those applications.
While not developed solely for WLANs, NDK's crystal units, TCXOs and surface-acoustic-wave (SAW) device for 5-GHz WLAN systems were adapted to meet the requirements of the application, said NDK. These specs include frequency, stability, size, efficiency, pass bandwidth and cost. The devices include the NX3225DA, NX4025DA and NX5032SA crystals; 5600 and NT4025 series TCXOs, and WF682A SAW device.
In January, NDK's NRS Technologies Inc. subsidiary completed the acquisition of NEC's SAW device business. NDK this month added a family of surface-mount SAW filters that meet North American mobile-phone standards. Available in 2.5 x 2 x 1.15-mm packages, the lead-free devices feature low insertion loss in passband ranges from 1.6 dB to 3 dB.
Among the newest products from NDK for Bluetooth applications is a series of ultrasmall, surface-mount quartz crystals. Exhibiting optimum electrical performance for Bluetooth applications, according to the company, the NX3225DA series is available in a 3.2 x 2.5 x 0.6-mm package with a frequency range of 16 to 55 MHz. Standard load capacitance is 10 picofarads with an equivalent series resistance of 100 ohms maximum in the frequency range of 16 MHz to 30 MHz (50 ohms maximum in 30- to 55-MHz range).
NDK America Inc.
Raltron Electronics Corp.