A 7-9 GHz LNA Utilizing Input Matching Filter for Out-of-Band Interference Rejection

This paper presents a 7-9 GHz low noise amplifier (LNA) microwave monolithic integrated circuit (MMIC) with out-of-band interference rejection performance. This is achieved by introducing the input matching filter technique, of which a filter type network is formed at the input to reject the out-of-band interference signal and also maintain good noise matching performance. Measurement results show that 25 dB gain and 1.6 dB noise figure has been achieved from 7 GHz to 9 GHz, and the interference rejection performance at 2.7 GHz is more than 67 dB. The size of the 3-stage LNA chip is 2 mm ×1 mm, and the total current is 10 mA from a+5 V power supply.