A fully integrated SiGe:C BiCMOS low noise amplifier (LNA) for Ultra-Wideband (UWB) has been implemented in a 0.4 um SiGe BiCMOS technology from Motorola Semiconductors which features a cut-off frequency of 46 GHz. The LNA exhibits a wide bandwidth, from 3 to 10.5 GHz, with a flat gain of 24 dB. This amplifier shows a noise figure below 4.4 dB over the whole bandwidth and achieves good return losses without any matching network. This 3 -10.5 GHz SiGe LNA design meet FCC PART15 restrictions for UWB technology.Index Terms -SiGe LNA, low noise, Darlington amplifier, UWB.