A 3.1 ~ 10.6 GHz Ultra-Wideband SiGe Low Noise Amplifier (LNA) is proposed. This low noise amplifier utilizes a current-reused technique to increase the gain and extend the bandwidth. We have a detailed analysis for the input matching, noise figure, gain and other features. The LNA was designed with the TSMC 0.35µm bipolar silicon-germanium (SiGe) processes. Simulation results show that the input reflection coefficient is less than-9dB, the output reflection coefficient is less than-10dB, the maximum power gain of 17 dB and the minimum noise factor (NF) of 2.35dB. The total power consumption is 6.2 mW with 2.5V power supply.