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In this paper, we demonstrate that the noise figure (NF) of a P+ active-area (AA) mesh inductor is much better than that of its standard version. In a P+AA mesh inductor, the AA with P+ implantation is added beneath it in the shape of a mesh to reduce its capacitive and magnetic coupling with the silicon substrate. Two 3.1-10.6-GHz CMOS ultrawideband (UWB) low-noise amplifiers (LNAs), one with P+ AA mesh inductors (AA mesh UWB LNA) and the other with standard inductors (STD UWB LNA), are implemented to study the effect of the P+ AA mesh on their performances. The results show that a 0.62-dB improvement in NF (from 0.8 to 0.18 dB) was achieved at 10.5 GHz for the input inductor LG1 if the P+ AA mesh had been added beneath it. In addition, the AA mesh UWB LNA achieved a low and flat NF of 3.365 plusmn 0.225 dB over the band of interest, notably better than that (4.64 plusmn 0.52 dB) of the STD UWB LNA.