New insights on RF CMOS stability related to bias, scaling, and temperature

Abstract

The stability issues of CMOS devices for RF applications were studied. The stability factor of MOS devices based on the small-signal model (SSM) parameters was derived, for the first time. The results reveal some new insights on the effects of biasing, and scaling parameters on the stability; and were subsequently confirmed by our experimental results. Our results also show that unconditional stability of RF CMOS devices can be obtained with proper biasing and device geometries. Finally, the effects of temperature on stability were also investigated. Our results suggest that careful attention needs to be paid for stable low temperature operation.

Temperature dependence of the power gain and scattering parametersS11 andS22 of an RF nMOSFET with advanced RF-CMOS technology

“…In the following, we apply the image theory to a vertical electric dipole (VED) in an isotropic medium above a half-space of another isotropic medium whose permittivity and permeability may have negative values. Such a medium was introduced by Victor Veselago in 1967 and has been variably called a left-handed medium [4,5], medium with negative refraction index [5,6], double-negative medium [7], or backward-wave medium [8]. The medium will here be called the Veselago medium for simplicity.…”

“…One of the main reasons is the availability of the transistors with high current-gain cutoff frequency f T and maximum oscillation frequency f MAX due to the rapid progress of silicon-process technologies [5,6]. Although many analytical expressions of the f T and f MAX of transistors have been derived [7][8][9], none of them includes the silicon-substrate effect. Therefore, in this paper, the analytical expressions of f T and f MAX of MOSFETs, including the silicon substrate effect, are reported.…”