Design and Fabrication of 77GHz HEMT Mixer Modules using Experimentally Optimized Antipodal Finline Transitions

77GHz PHEMT gate mixer module and resistive mixer module were fabricated for automotive applications using LG-CIT low noise PHEMT process and WR12-to-microstrip antipodal finline transitions. Experimental optimization of the finline transitions was attempted for wideband operation and low insertion loss by adjusting geometrical design parameters. The average insertion loss was measured to be 0.74dB per transition in 75~90GHz. The fabricated gate mixer module and the resistive mixer module showed very good conversion loss of 2dB and 10.3dB, respectively, including finline transition loss and IF cable loss, which were very competitive performances.