Silicon-on-Sapphire, a replacement for gallium arsenide?

Silicon-on-sapphire (SOS) was invented in 1961 and as such is the first of the SOI technologies. Its original purpose was to provide radiation tolerant circuits for satellites and missiles. Now, SOS is ready to displace gallium arsenide (GaAs) as the technology of choice for RF communications in commercial applications. What are the reasons for this? In this paper, I will share what we have learned at Peregrine semiconductor about how to use CMOS for RF devices and why silicon will eventually displace GaAs from many RF applications.