In this paper, the effect of the gate, channel, and substrate resistances on the MOSFET's input and output ports has been investigated when the CMOS technology is scaled from the 0.18 /spl mu/m to the sub-100 nm regime by analyzing S-parameter measurements. Results showed new features to be considered in the modeling of the input port of sub-100 nm devices, while the output port remains almost insensitive to technology scaling. Additionally, an enhanced model for the gate electrode impedance and a novel substrate resistance extraction technique are proposed to study the device's characteristics at RF.