Design of a wideband CMOS variable-gain low noise amplifier

This paper presents the design of a wideband CMOS variable-gain low-noise amplifier (LNA) working in the RF band 0.9-5 GHz. In this design, a digitally-controlled variable gain amplifier (VGA) based on a signal-summing topology are used, and a binary-weighted switching technique is employed to control the aspect ratios of transistors. The LNA is fabricated in a 0.18μm CMOS process. The post simulation results show that the proposed LNA has a voltage gain from 3 dB to 24 dB with a 3 dB gain step in the frequency range from 0.9 GHz to 5 GHz. At maximum gain mode, the NF and the IIP₃ of the LNA are 5 dB and -12.6dBm, respectively. The return loss Su and S₂₂ of the LNA are less than -10 dB. The proposed wideband VGA consumes a power of 20 mW from 1.8 V supply.