Designed for 3.5 GHz fixed wireless applications, Alpha Industries' new AL108-338 packaged GaAs PHEMT switchable-gain LNA is a leadless, surface mount QFN-16, 4 x 4 mm, MMIC package that yields low noise, good 50 Ohm match, high gain and powerful P1dB performance.

The AL108-338 matches input and output to 50 Ohm. Key specifications include a frequency range of 3.2 to 3.8 GHz, adjustable gain, +7 dBm output power, +17 dBm output IP3, and 2.7 dB noise. Powered by a 5 V supply, the AL108-338 provides a 10 dB gain adjustment range.

Alpha Industries Inc., 25 Computer Drive, Haverhill, MA 01832. Tel: 978-241-7000, Fax: 978-241-7906. Email: sales @alphaind.com; Web: www.alphaind.com

Alpha Industries is a provider of RF integrated circuit-based solutions, including semiconductors and ceramic components, for the broadband and wireless communications markets. Alpha's switches, power amplifiers and discrete semiconductors are used by the world's leading broadband, infrastructure and wireless communications companies to enhance the speed, quality and performance of voice, data and video. The Company's Alpha Integration Platform™ (aiIP™) is a manufacturing, packaging and design technique that reduces design complexity and improves the OEM's overall time to market for new products.

Editorial Contact:
Alpha Industries, Inc.
Tel: 978-241-7000
Fax: 978-241-7906
Web site: www.alphaind.com

First, a little background on Alpha and where it's going. Alpha Industries and Conexant recently announced they will merge and anticipate that the merger will be completed in the quarter ending June 30, 2002. In addition to approval by Alpha stockholders, the merger is subject to receipt of a ruling by the IRS that the spin-off of Conexant's wireless communications business immediately prior to the merger will be tax-free to Conexant stockholders and satisfaction of all other closing conditions. The new merged company will then purchase Conexant's semiconductor assembly, module manufacturing, and testing facility in Mexicali, Mexico. Conexant Systems' new spin-off foundry company was recently named Jazz Semiconductor Inc.

Now, to the meat of the matter, the AL108-338 packaged GaAs PHEMT switchable-gain LNA. The most important spec for an amplifier is not gain but the noise figure. This part shows a respectable 2.7 dB noise figure. LNAs also are rated in noise temperature specified in degrees Kelvin with the lower the degree rating the better the LNA. Although this part, in general, shows good specifications, I would like to have seen a noise temperature given.

Other good figures of merit, that Alpha defined, were the 10 dB gain adjustment, and the +17 dBm output third order intercept point, the IP3. A poor third order intercept point is one of the factors that causes a device to mix signals together resulting in intermodulation. The result is a system that invites even moderate signals to overload and degrade an entire system.

If you are looking to learn more about the subject of LNAs you can find a NetSeminar that compares design simulations with measured results, and investigates how to make narrow bandwidth noise figure measurements when a filter is combined with the LNA. An overview of some of the uncertainties involved in noise figure is also covered.

The AL108-338 package is priced at $1.45 per part in quantities of 100,000.