Abstract: A novel ultra-wideband(UWB) low noise and high gain Darlington amplifier is presented based on the traditional narrow-band Darlington amplifier.In the new amplifier,the high-frequency transistors,and the compensation techniques of inductor and positive real resistance are adopted to keep the advantage of high gain of Darlington amplifier,and to achieve low noise,good input and output match,and good wideband stability.The simulation results show that the new amplifier has high gain of 21 dB with variation less than 0.3 dB,low noise figure from 1.5 to 2.1 dB,matched input and output reflections(S11,S22) less than-14 dB,and good stability in the frequency range from 3.1 to 6 GHz.