A capacitor cross-coupled common-gate low-noise amplifier

The conventional common-gate low-noise amplifier (CGLNA) exhibits a relatively high noise figure (NF) at low operating frequencies relative to the MOSFET f_T, which has limited its adoption notwithstanding its superior linearity, input matching, and stability compared to the inductively degenerated common-source LNA (CSLNA). A capacitor cross-coupled g_m-boosting scheme is described that improves the NF and retains the advantages of the CGLNA topology. The technique also enables a significant reduction in current consumption. A fully integrated capacitor cross-coupled CGLNA implemented in 180-nm CMOS validates the g_m-boosting technique. It achieves a measured NF of 3.0 dB at 6.0 GHz and consumes only 3.6 mA from 1.8 V; the measured input-referred third-order intercept ( IIP3) value is 11.4 dBm. The capacitor cross-coupled g_m-boosted CGLNA is attractive for low-power fully integrated applications in fine-line CMOS technologies.