Electronic Design

Tri-Band Power Amplifier Enables Worldwide GSM Mobile Phones

A new triband power amplifier, the CX77302, enables GSM mobile phones that can be used around the world. Designed by Conexant Systems, this device operates in the 900-, 1800-, and 1900-MHz communications bands. Consequently, it provides a singular multichip-module (MCM) solution for all networks using the GSM standard.

The power amplifier MCM comprises dual HBT amplifiers on a single gallium arsenide (GaAs) die. It also includes a CMOS interface IC that serves as a current buffer and limiter for the amplifier blocks. Plus, the MCM contains impedance-matching circuits capable of input and output matching to 50 Ω. While one amplifier block operates in the enhanced GSM900 band, the other supports both DCS1800 and PCS1900 bands.

According to Conexant, the amplifiers are biased through the CMOS chip for maximum efficiency. For instance, typical power-added efficiency (PAE) for the two-stage power amplifier operating in the enhanced GSM band is 55%. Meanwhile, the three-stage amplifier in the DCS/PCS band offers a typical PAE of 45%.

In addition, the power amplifier supports two-slot transmission, allowing it to process twice as much information as traditional GSM power amplifiers. Therefore, the amplifier can handle general packet-radio service (GPRS). GPRS phones will give an extension to existing GSM networks that promise a new array of wireless services with "always-on" data efficiency. These phones are expected to become commercially available later this year.

"Our new triband power amplifiers provide the capability to work in all U.S., European, and Asian GSM networks in a single-amplifier package," says Moiz Beguwala, senior vice president and general manager for Conexant's wireless communications division. Beguwala also adds that, "These devices provide the integration and features OEMs need to quickly introduce new phone models supporting the latest mobile data services like GPRS."

Conexant's GSM power amplifiers are made to complement the company's complete line of GSM system solutions. With this in mind, Conexant plans to debut a full system solution for GPRS phones later this year. The 3-V CX77302 is packaged as a 9-x-11 laminate MCM with 16 pins. In quantities of 10,000, it's available for $4.85.

Conexant Systems Inc., 4311 Jamboree Rd., Newport Beach, CA 92660-3007; (949) 483-4600; www.conexant.com.

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TAGS: Mobile
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