A wide-band low-noise amplifier with double loop feedback

There is increasing interest in wireless receivers that can work with different standards at different frequencies. The usual way of implementing a low noise amplifier (LNA) block in such a receiver is to use separate narrowband LNAs. In this paper, a wideband LNA is presented, with negative feedback by means of a double loop feedback network to achieve simultaneously a low noise figure and input matched impedance for a wide range of frequencies. The designed LNA has a noise figure lower than 3 dB, input impedance matched to 50 Ω and a gain above 12 dB for a frequency range between 700 MHz; and 5 GHz. The LNA has been designed in 0.18 μm CMOS technology from National Semiconductor. It consumes 18.9 mW for a supply voltage of 1.8 V.