A CMOS Active Balun-LNA With Imbalance Correction and Noise Cancelling

This paper presents an active balun topology with differential imbalance correction and noise cancelling schemes. The imbalance correction scheme can effectively ameliorate both the magnitude and phase errors induced by circuit asymmetry, parasitic and layout mismatch. Noise cancelling exists in each individual stage, which leads to good noise performance. With sufficient gain and low noise figure, this balun can also work as a low noise amplifier (LNA) in RF front end. Implemented in 65nm CMOS process, the balun-LNA exhibits maximum power gain of 16dB, minimum noise figure of 3.8dB and input matching better than -20dB. The measured magnitude and phase errors are less than 0.6dB and 7 degrees, respectively.