A 3.6mW differential common-gate CMOS LNA with positive-negative feedback

A common-gate (CG) LNA has been widely investigated because it features superior bandwidth, linearity, stability, and robustness to PVT variations compared to a common-source (CS) topology. In spite of these advantages, the dependence of gain and NF on the restricted transconductance (gm) renders this topology unsuitable for various wireless applications. The input impedance of a CG LNA is simplified as Mgm, and the noise factor is inversely proportional to gm. In order to achieve high gain and low NF, gm should be increased, which deteriorates the 50Omega input impedance matching for a conventional CG LNA.