Serendipitous noise reduction in inductively degenerated CMOS RF LNAs

In English The design of radio-frequency inductively-degenerated
CMOS low-noise-amplifiers does not follow the
guidelines for minimum noise figure. Nonetheless,
state-of-the-art implementations achieve noise figure
values very close to the theoretical minimum. In this
brief contribution, we point out that this is due to the
effect of the parasitic overlap capacitances in the MOS
device acting as transconductor. In particular, we
show that overlap capacitances lead to a significant
induced-gate-noise reduction, especially when deep
sub-micron CMOS processes are used.