A 10-15 GHz CMOS Balun-LNA Using Folded Three-Coil Transformer

This paper presents a 10-15 GHz low noise amplifier (LNA) in 40nm CMOS technology. It consists of cascode stage and common source (CS) stage. The transformer between cascode stage and CS stage is applied as a passive balun to achieve single-to-differential conversion. By utilizing a folded three-coil transformer in input matching network, compact layout and wideband input matching are achieved. In addition, the coupled coils boost the equivalent transconductance of input transistor and realize noise reduction simultaneously. The simulated results show outstanding performance. S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf> is lower than -10 dB from 7.2 GHz to 18.8 GHz. Within the operating frequency range of 10-15 GHz, the noise figure (NF) is below 2.15 dB and the minimum NF is 2.02 dB. The average gain is 22.1 dB and the gain flatness is ±1.1 dB. The power consumption is 23.3 mW.