An 18 GHz low noise high linearity active mixer in SiGe

In this paper, the design and measured results of an active double-balanced direct down-conversion mixer at 18 GHz is presented. The mixer, which is fabricated in IBM´s 45-GHz f_t SiGe BiCMOS process achieves a 4.5 dB conversion gain, a 7.1 dB double sideband noise figure, an IIP₃ of -1 dBm, an IIP₂ of 20.3 dBm, and a l-dB compression point at 12.2 dBm output power. The mixer DC power consumption is 16.5 mW with a 3.3 V supply. To the authors´ knowledge, the design achieves the highest figure of merit among published direct down-conversion mixers operating at similar frequencies in comparable Si-based process.