Effects of hot-carrier stress on the performance of CMOS Low Noise Amplifier

The effects of DC hot-carrier stress on the performance of a CMOS Low Noise Amplifier (LNA) are investigated. It was observed that the main effects caused by stress on the NMOSFETs in the LNA are a decrease of the transconductance g_m and an increase of the output conductance g_ds. As a result of these changes, the power gain of the amplifier S₂₁, input matching S₁₁ and output matching S₂₂ are deteriorated. The linearity of the LNA improved after stress and this is believed to be due to the improvement in the linearity of the I-V characteristics of the transistors in the circuit at the particular biasing points the measurements were made. The noise figure of the circuit also increases after hot carrier stress which is believed to be due to increase in channel thermal noise caused by hot carriers.