A 3.55 dB NF Ultra-Compact Noise-Optimized LNA for 5G mm-Wave Bands in 65nm CMOS

A noise-optimized LNA at 30GHz for 5G millimeterwave bands is designed in this paper. The focus is on the optimization of the input device for noise performance and reducing the difference between noise figure (NF) and minimum noise figure (NFmin). The conventional approach of input biasing that maximizes f
_T
/f
_max
to improve noise figure is found to be sub-optimal. The dependence of NF, NFmin and noise-optimum impedance (Z
_opt
) on the input transistor is studied and the existence of an optimal biasing point is demonstrated and explained. The dependence of Z
_opt
on the gate inductor is exploited to bring NF closer to NFmin. A two stage cascode LNA is designed at 30GHz in a commercial 65nm CMOS process. Having a core area of 0.42×0.32mm
²
, the LNA achieves 22.3dB gain and 3.55dB noise figure at a DC power consumption of only 7mW.