Abstract: In this paper, the design and simulation of an ultra-wide band CMOS low noise amplifier (LNA) is reported.By using of dual-Channel topology, the input matching and flat gain as well as low noise are achieved simultaneously.The LNA was simulated by ADS TSMC 0.13 μm CMOS design kit, obtaining a maximum gain of 14.2dB and ⅡP3 of-4dBm at around 8GHz.The input return loss is under-10.2dB, meanwhile output counterpart better than-10.89dB.The noise figure (NF) falls to 1.46dB monotonically, and the whole hierarchy consumes fair low power and maximum gain rippling is low.