Importance of $V_{\rm th}$ and Substrate Resistance Control for RF Performance Improvement in MOSFETs

Transistor scaling with the CMOS technology advancement results in f _max saturation in contrast to fT improvement. Effective improvement methods for such saturated f _max are presented to the transistors fabricated by 45- and 65-nm low standby power CMOS technology. The primary parameters investigated are V _th optimization through adjusting the channel implantation and R _sub control through adjusting the active to substrate contact spacing. It is demonstrated that V _th optimization and R _sub control result in more than 20% and 10% improvements for f _max, respectively.