Hot-carrier reliability of submicron NMOSFETs and integrated NMOS low noise amplifiers

The effects of hot-carrier stress (HCS) on the performance of NMOSFETs and a fully integrated low noise amplifier (LNA) made of NMOSFETs in a 0.18μm CMOS technology are studied. The main effects of HCS on single NMOSFETs are an increase in threshold voltage and a decrease in channel carrier mobility, which lead to a drop in the biasing current of the transistors. In the small-signal model of the transistor, hot-carrier effects appear as a decrease in the transconductance and an increase of the output conductance. No clear change was observed in the parasitic gate–source and gate–drain capacitances in the devices under test due to hot carriers. The main effects of hot carriers in the LNA were a drop of the power gain and an increase of its noise figure. The input and output matching, S11 and S22, slightly increased after hot-carrier stress. The third- order input-referred intercept point (IIP3) of the LNA improved after stress. This is believed to be due to the improvement of the linearity of the current–voltage (I–V) characteristics of the transistors in the LNA at the particular operating point where they were biased.