Electronic Design

Fortify Embedded Wi-Fi With RF Power Amps

Advanced applications that embed 2.4-GHz 802.11b/g Wi-Fi, such as laptops, cell phones, PDAs, and Voice-over-Wi-Fi phones, have new power amplifiers at their disposal. Designed by SiGe Semiconductor, the RangeCharger RF amps feature increased integration for lower parts count and cost, smaller size, and reduced current drain for higher power efficiency.

The SE2550L is a complete front-end module with all of the circuitry needed to interface the antenna and radio chip. It includes a high-performance power amplifier, a power detector, digital enable control, a single-pole double-throw (SPDT) transmit/
receive switch, a harmonic filter, and all of the input and output matching circuits for a 50-V antenna.

The power amp's overall gain is 29 dB with an output power of +19 dB in 802.11b mode and +16 dBm in 802.11g mode. The 802.11g error vector magnitude (EVM) is 3% at +16 dBm. The digital enable control can be connected directly to the external CMOS baseband or transceiver chip. The power detector's selectable positive and negative slopes can adapt to virtually any external chips.

The SE2523L power amplifier is similar to the amp in the SE2550L. But while it has a power detector and a bit more output power, it lacks the switch and impedance matching circuits. Overall gain is 31 dB with a power output of +23 dB for 802.11b operation and +18 dBm for 802.11g operation. EVM is 3% at the 11g power level.

Both chips operate from a 2.7- to 3.6-V supply. The SE2550L comes in an 18-pin QFN package measuring 4 by 4.5 by 0.6 mm. The SE2523L is housed in a 16-pin, 3- by 3-mm QFN package. In 100,000-unit quantities, the SE2550L and SE2523L cost $1.40 and $0.70, respectively. Application boards are available. Both devices are sampling now.

SiGe Semiconductor Inc.

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