This paper has designed a 5.25 GHz low noise amplifier. We used a low noise field effect tube (ATF36077) to design two slopes of low noise amplifier which improved the gain, and used a cross junction structure to make the input matching circuit. Besides, the amplifier enhanced the stability of the circuit through adding the microstrip in the source of 36077 as a negative feedback. The measurement results show in the 4.9 GHz to 5.3 GHz frequency band, low noise amplifier gain is 21 dB, less noise factor is less than 2 dB, and bandwidth is about 400MHz.
