Advanced thin-film silicon-on-sapphire technology: Microwave circuit applications

This paper reviews the prospects of thin-film silicon-on-sapphire (TFSOS) CMOS technology in microwave applications in the 1-5 GHz regime and beyond and presents the first demonstration of microwave integrated circuits based on this technology. MOSFET's optimized for microwave use, with 0.5-mu m optically defined gate lengths and a T-gate structure, have f(t) values of 25 GHz (14 GHz) and f(max) values of 66 GHz (41 GHz) for n-channel (p-channel) devices and have noise figure values below 1 dB at 2 GHz, some of the best reported performance characteristics of any silicon-based MOSFET's to date. On-chip spiral inductors exhibit quality factors above ten. Circuit performance compares favorably with that of other CMOS-based technologies and approach performance levels similar to those obtained by silicon bipolar technologies. The results demonstrate the significant potential of this technology for microwave applications.