This paper describes using notch filters for improving the gain and gain flatness of an UWB CMOS LNA designed with a 0.13µ m CMOS technology. Also, the performance of LNA is examined by replacing the passive inductances in notch filters with Q-enhanced cascade-grounded active inductors to decrease the silicon area. Simulation results illustrate that both passive and active notch filters at 2.4GHz approximately improves the gain flatness by 0.75dB, while the gain performance with passive notch is about 2dB better. In addition, passive notch filters at 2.9GHz, in parallel with a passive and active notch at 5.2GHz for interference reduction, increases the gain by 3dB and 4dB, respectively.