A multiband low noise amplifier with a switchable Gm active shunt feedback for SDRs

摘要

This paper presents a reconfigurable low noise amplifier (LNA) with simultaneous tunable input matching and output response. Switching of the input matching is achieved by using an active shunt feedback circuit including a source follower whose transconductance is switched by a bank of switchable current sources. The LNA makes use of dual LC tanks to switch four frequency bands including 1.8GHz, 2.4GHz, 3.5GHz and 5.2GHz. One LC tank switches between 5.2GHz and 3.5GHz while the other tank switches between 2.4GHz and 1.8GHz. The LNA achieves a NF as low as 2.8dB and an IIP3 as high as ???3.45dBm while consuming a maximum power of 7.2mW at a 1.8V supply. The LNA occupies an active area of 0.63mm2.