Effects of Hot-Carrier Stress on the Performance of CMOS Low-Noise Amplifiers

The effects of direct current (dc) hot-carrier stress on the characteristics of NMOSFETs and a fully integrated low-noise amplifier (LNA) made of NMOSFETs in an 0.18-$\mu{\rm m}$ complementary MOS (CMOS) technology are investigated. The increase in threshold voltage and decrease in mobility caused by hot carriers lead to a drop in the biasing current of the transistors. These effects lead to a decrease in the transconductance and an increase of the output conductance of the device. No measurable change in the parasitic gate–source and gate–drain capacitances in the devices under test were observed due to hot carriers. In the LNA, the important effects caused by hot carriers were a drop of the power gain and an increase of the noise figure. A slight increase in the input and output matching $S_{11}$ and $S_{22}$, respectively, after hot-carrier stress was observed. The linearity parameter IIP3 of the LNA improved after stress. This is believed to be due to the improvement of the linearity of the I–V characteristics of the transistors in the LNA at the particular operating point where the measurements were performed.