Effects of back gate bias on radio-frequency performance in partially depleted silicon-on-inslator nMOSFETs

Abstract

The effects of back gate bias (BGEs) on radio-frequency (RF) performances in PD SOI nMOSFETs are presented in this paper. Floating body (FB) device, T-gate body-contact (TB) device, and tunnel diode body-contact (TDBC) device, of which the supply voltages are all 1.2 V, are compared under different back gate biases by different figures of merit, such as cut-off frequency (fT), maximum frequency of oscillation (fmax), etc. Because of the lack of a back gate conducting channel, the drain conductance (gd) of TDBC transistor shows a smaller degradation than those of the others, and the trans-conductance (gm) of TDBC is almost independent of back gate bias. The values of fT of TDBC are also kept nearly constant under different back gate biases. However, RF performances of FB and TB each show a significant degradation when the back gate bias is larger than ∼20 V. The results indicate that TDBC structures could effectively improve the back gate bias in RF performance.