A low noise ultra wideband amplifier may be designed by using two transformers in the input as well as in the output of the bipolar junction transistor(BJT) amplifier in the frequency range from 45 MHz to 300 MHz. From the equivalent circuit model of BJT, the noise figure of this amplifier is calculated. The trade-off of the power gain and the noise figure is carefully compared to achieve about 1.7 dB for the noise figure and 19 dB of power gain over the above mentioned frequency range. Parameters affecting the noise figure, power gain and the frequency band are the distributed resistance between the emitter and the base, external input side source resistance, the input reactance of the transistor and its bias current. The designed parameters are experimentally verified by measuring the power gain and the noise figure.
