It is good to see a potentially market viable linear CMOS PA come to market. Blacksand announced sampling their 3G CMOS PAs a couple of months ago, so more than player is ready to enter the sand box.
The Javelin proposal is an interesting approach to differentiate from the current GaAs PA solutions, but it is a circuit solution and not a CMOS versus GaAs technology solution. Integrating the bandpass response into the PA design is what saves the BOM cost. The GaAs PA folks could probably find an equivalent solution if the market pushes them into doing it.
However, there are questions about the approach that need answering.
1. How well controlled is the bandpass response from part-to-part? Is the 15dB Rx rejection a guaranteed minimum rejection.
2. What is the worst case gain variation across the band. Small shifts in the response could make a big change in gain across the band. Perhaps this is ok to some extent since 2dB of filter loss has been eliminated.
There are market questions too...
Some GaAs PAs are multi-band such that the same PA is used across several near bands (800MHz-900MHz and 1.8GHz-2GHz). Such PAs offer cost savings by using one PA where there would normally be separate PAs for each band. So, how does the Javelin bandpass approach address this?
There is also a trend in RFIC research towards designing transmitters with very low Rxband noise (below -160dBm/Hz) to eliminate the Tx SAW filter.
Despite these questions, I hope linear CMOS PAs do make their way into the market. Once they get beyond having their foot in the door then the game will be on between CMOS and GaAs PAs.
We've been hearing about CMOS PA's for years and though there has been impressive improvements and design wins, still no real threat to GaAs PA's. GaAs ASP's are below 50 cents/module and the major players all own their own fabs. CMOS has its advantage with very low cost handsets, mainly 2G/2.5G, in developing countries and with second and third-tier OEM's in places like India and China.
I remember the hype about SiGe PA's a decade ago and the linearity, PAE and reliability still could not match GaAs. The only major SiGe player just got bought by Skyworks and maybe had major design win slots with WLAN and BT.
BTW, RFAxis is mostly hype and has a bulk of their design wins with ZigBee module companies and small ODM's.
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