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SiGe Semiconductor power amp cuts space

Posted: 25 Sep 2003 ?? ?Print Version ?Bookmark and Share

Keywords:sige semiconductor? 802.11b/g? wlan power amplifier? power amplifier? rangecharger?

SiGe Semiconductor Inc. has added an on-board directional coupler, power detector, power-enable switch and bias-control circuitry to its 802.11b/g WLAN power amplifier (PA) lineup. The move is part of a drive to lower the space requirements and cost of WLAN front-ends, while also capitalizing on the silicon-germanium-based PA's established linearity, stability and throughput capabilities.

"Our story is lower EVM [error vector magnitude], high output power and robust power detection," said Andrew Parolin, product line manager for WLAN power amps at SiGe Semiconductor. All of those features are essential for high throughput at greater range, he said.

The new PA, the RangeCharger SE2525L, is a more-integrated version of the company's SE2529L, which was included in Broadcom Corp.'s 54g WLAN reference design and in a full front-end module that SiGe announced this spring. The two have much the same performance. In 802.11g mode with a power output of 19dBm, the SE2525L has an EVM of 3 percent, or 2.5 percent at 17dBm. In 802.11b mode, it has an adjacent-channel power-rejection ratio of -33dBc at 23dBm output power.

But the 2525L is more integrated. "We added on-board enable and ramping circuitry, allowing one digital CMOS pin to now turn the PA on and off," said Parolin, saving 10 to 12 cents in external circuitry. The PA also integrates the power detector. "Our strategy is quite novel in that it has an input and output pin that allows you to use an external coupler while still using the on-board IC detector," Parolin said. Most PA vendors that integrate the detector don't give a customer access to it.

Higher integration has knocked about 40 cents off the cost of the final design, and has also reduced the current draw from about 260mA to 160mA in .11g mode, and from 200mA to 70mA in .11b mode, Parolin said.

The SE2525L is sampling now in a 4-by-4mm 16-pin LPCC package and is priced at $1.59 each in quantities of 10,000.

- Patrick Mannion

EE Times

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