28-nm FDSOI nMOSFET RF Figures of Merits and Parasitic Elements Extraction at Cryogenic Temperature Down to 77 K

Abstract

This paper presents detailed RF characterization of 28-nm FDSOI nMOSFETs at cryogenic temperatures down to 77 K. Two main RF figures of merit (FoM), i.e., current gain cutoff frequency (fT) and maximum oscillation frequency (fmax), as well as elements of small-signal equivalent circuit are extracted from the measured S-parameters. Increases of fT and fmax by about 85 GHz and about 30 GHz, respectively, are demonstrated at 77 K. The observed behavior of RF FoMs versus temperature is discussed in terms of small-signal equivalent circuit elements, both intrinsic and extrinsic (parasitics). This paper suggests 28-nm FDSOI as a good candidate for future cryogenic applications.

Keywords

• FDSOI
• UTBB MOSFETs
• RF figures of merit (FoM)
• cryogenic temperature
• parasitic elements