A low-power low-noise amplifier (LNA) for ultra wideband (UWB) radiosystems is presented. The microwave monolithic integrated circuit(MMIC) has been fabricated using a commercial 0.25-?m silicon-germanium(SiGe) bipolar CMOS (BiCMOS) technology. The amplifier uses peakingand feedback techniques to optimize its gain, bandwidth and impedancematching. It operates from 3.4 to 6.9 GHz, which corresponds withthe low end of the available UWB radio spectrum. The LNA has a peakgain of 10 dB and a noise figure less than 5 dB over the entire bandwidth.The circuit consumes only 3.5 mW using a 1-V supply voltage. A figureof merit (FoM) for LNAs considering bandwidth. gain, noise, powerconsumption, and technology is proposed. The realized LNA circuitis compared with other recently published low-power LNA designs andshows the highest reported FoM.