Amplifiers: Where the Power Is

The power amplifier on Wi-Fi chips is the circuit that controls the juice, and as such can also help to extend range. Many Wi-Fi chip vendors make their own PAs, but a growing number of PAs are coming in the form of front-end modules that connect with almost any type of 802.11-based chipset.

The move toward modules is one of the reasons why Strategy Analytics believes PAs are poised for significant growth in the coming years — and why PA modularity will be a core factor in moving Wi-Fi into platforms beyond computers, PDAs and phones.

There are two main PA creation technologies. Silicon Germanium (SiGe) is used to make PAs that work with 802.11b/g, which uses the 2.5GHz unlicensed radio frequency (RF) spectrum. PAs made using the Galium Arsinide (GaAs) process have better efficiency at higher frequencies, and are used more often with 5GHz 802.11a. Chris Taylor, Director of RF & Wireless Components at Strategy Analytics, says that’s unlikely to change, as “no one’s come up with a SiGe power amp at a higher frequency yet.”

“It’s possible to put the PA on the chip if you’re going a short distance with the signal,” says Taylor. “But to get the full specification [distance], you generally need external power amplifiers.”

The successful companies seem to be those that are able to adapt their existing PAs for the cell phone business to work with Wi-Fi. Taylor cites examples like RF Micro Devices and SkyWorks, in particular: “We think they’re in a good position because of their experience in handsets,” he says.

This move toward PA modules is likely to have taken place even if handsets were not a big factor. Taylor isn’t even sure that Wi-Fi handsets will be the key market for the modular PAs, since VoWi-Fi handsets will likely use packages with the baseband, MAC and PA all combined to keep the size down. Besides, as much as everyone thinks Wi-Fi phones are going to explode as a market — including Strategy Analytics — Taylor says “it’s still very small.”

The future 802.11n high speed specification, which will likely support backward compatibility with both 5GHz and 2.4GHz WLANs, is likely to require using two PAs, one SiGE and one GaAs.

“The future is good either way for modules,” says Taylor.

Strategy Analytics also reported that with so many Wi-Fi chipmakers out there today — they count 58 — and with three of them dominating the market (Atheros, Broadcom and Intel), it expects only 20 802.11 chip makers to survive the next five years intact. Taylor was loath to mention anyone in particular, but admitted there are always questions about the future Conexant, which absorbed the Intersil/Globespan-Virata PRISM line of chips which once dominated the industry. As of last year, the company was facing multiple class action lawsuits over its mergers.  

On the other side, he calls chipmaker Marvell “very nimble,” and one that’s likely to weather competitive storms.

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