A New Ultra-Wideband Low Noise Amplifier With Continuous Gain Control

This paper presents a new variable gain low noise amplifier (VG-LNA) for ultra-wideband (UWB) applications. The proposed VG-LNA uses a common-source (CS) with a shunt-shunt active feedback as an input stage to realize input matching and partial noise cancelling. An output stage consists of a gain-boosted CS cascode and a gain control circuit that moves the high resonant frequency to higher frequencies and provides flatness gain. The direct power gain (S21) is continuously controlled without significant degradation in the input return loss (S11) and noise figure. The proposed VG-LNA is designed and simulated using RF-TSMC 0.18 μm CMOS technology by Advanced Design System (ADS). Simulation results show a maximum flat power gain (S21) of 14 dB with a noise figure (NF) lower than 3.6 dB and an input impedance matching (S11) less than –10 dB over the wide bandwidth of 3.5 to 13.5 GHz. Its power consumption is 12 mW with low power supply of 0.9 V. In addition, the power gain ranges from 7 to 14 dB at the center frequency of 8.5 GHz.