A 20GHz low noise CMOS active baiun using asymmetric transformer

A 20GHz-band low noise CMOS active balun is presented. The proposed circuit utilizes asymmetric transformer to CG-CS(Common Gate-Common Source) noise canceling active balun, in order to lower amplitude and phase errors in high frequency operation. Analysis with circuit simulation and measurement results verifies that the proposed circuit effectively reduce noise figure at 20GHz band while keeping differential output balance. The proposed circuit is fabricated in 0.13um CMOS process, and achieved noise figure of 7.2dB at 21GHz which is 2dB lower than active balun with symmetric transformer.