Highly Linear 60-GHz SiGe Downconversion/Upconversion Mixers
A linear RF to IF downconversion and IF to RF upconversion mixers for 60-GHz transceivers were implemented in 0.13-μm SiGe technology. The mixers were implemented using a mixing core only topology for enhanced linearity, with no local oscillator (LO) buffers and a transformer-based matching network for IF frequencies. The downconversion mixer at full attenuation shows a minimum of 10-dBm IIP3 and maximum measured loss of 6.5 dB within the entire 57-66 GHz frequency band. Without attenuation, the conversion gain is above 4 dB, with better than 2-dBm IIP3 and a noise figure maximum value of 14 dB within the band. The transmit mixer exhibits less than 2.5-dB conversion loss, better than 7.5-dBm OIP3 with minimal temperature variations. For improved LO to RF isolation, separated dc bias control is used in the mixing devices providing over 46-dBc LO suppression within the band. The mixers occupy only 0.47 and 0.22 mm2 consuming 56 mW for downconversion mixer with IF amplifier and 27 mW for upconversion mixer.