The Death of GaAs?
The answer, according to Liam Devlin, CEO of Plextek RFI, is “Not any time soon, but the competition is increasing”.
Cellular communications products currently account for over 50% of all GaAs sales revenue. It is clear that the front-end switch function, which until recently was dominated by GaAs PHEMT devices, has now switched to Si on Insulator (SoI) technology. The reasons for this are comparable, or in some cases superior, performance combined with the fact that all control logic can be included on the switch IC rather than requiring a separate CMOS control IC as in the case of the PHEMT switches.
The PA function is still dominated by GaAs HBT, even in low cost handsets, despite the fact that CMOS PAs have been available for a number of years and are now used in some commercially available products. The panel provided data to show that although the cost per square mm of CMOS is cheaper than that of GaAs, the CMOS PAs occupy more area and the resulting PAs are similar in cost. As GaAs HBT PAs also tend to offer superior efficiency, this has left them in pole position for this function. The view that CMOS would become the technology of preference for entry level handsets with GaAs HBT being preferred for higher-end products was also expressed.
Although the panel discussion at IMS 2013 focused on the challenge of Si technologies to key applications for GaAs, the challenge from GaN was also covered. GaN technology is particularly well suited to the implementation of RF and microwave High Power Amplifiers (HPAs), an area of dominance for GaAs technologies. GaN is currently considerably more expensive than GaAs but is capable of realizing HPAs with higher output powers and efficiency. The level of interest in GaN was clear across the conference and exhibition as a whole, but at the moment the higher costs mean that it is only used when GaAs capability runs out of steam.
Ultimately end users purchase products based on a trade off of price and performance rather than the elements used in the manufacture of the ICs. It is the market that will decide on the fate of GaAs but the GaAs manufacturers and suppliers are still performing well and this doesn’t look set to end in the immediate future.
[Originally presented as part of a Panel Session with the same title at the International Microwave Symposium 2013]