This paper presents an ultra-wide band, fully balanced, down converting frequency mixer MMIC that was designed for a high dynamic range radar receiver system. The multi-tanh triplet principle is used to achieve high linearity and good noise matching performance. A state of the art 0.13 µm SiGe BiCMOS process is employed for enabling an ultra-wide band operation. The design features minimum double side band noise figure of 10 dB, conversion gain of 9 dB, very compact active area of 0.014 mm2, whereas the 1 dB compression point is reached at the input power level of −8 dBm. To the best knowledge of the author, the proposed mixer MMIC outperforms the state of the art reported active mixer designs in terms of figure of merit, typically defined for evaluating frequency mixers.