A highly linear wideband variable gain CMOS balun-LNA

This paper presents a highly linear wideband variable gain CMOS Low Noise Amplifier (LNA) that supports single-ended input while providing differential output. The impacts of biasing and parasitic capacitance on gain, noise and linearity are investigated and a new gain tuning method is proposed. The proposed wideband LNA is designed in a 0.18 µm CMOS process. The post-layout simulations show the proposed LNA has a maximum gain of 18 dB and a tunable gain range of 23.1 dB. The LNA shows a noise figure (NF) from 2.16 dB to 2.31 dB at maximum gain mode, a third-order input-referred intercept point (IIP3) of 10.36 dBm and an input referred 1-dB compression point of 1.66 dBm. The return loss S11 is better than −11.0 dB in the frequency range from 470 to 870 MHz. The proposed LNA consumes 5.93 mA from a 1.8 V power supply.