Low-Loss 140-175 GHz MMIC-to-Waveguide Transitions and MMIC-to-MMIC Interconnections

This work presents two types of direct MMIC-to-waveguide (WG) transitions and two types of MMIC-to-MMIC interconnections between 140 to 175 GHz. A periodic electromagnetic bandgap (EBG) structure is used in the MMIC-to-WG transitions to suppress unwanted resonances and help the coupling between the microstrip mode and the waveguide mode. Measurement of the two types of MMIC-to-WG transitions shows 0.38 to 0.63 dB and 0.32 to 0.62 dB insertion loss respectively. Insertion loss of hot-via based MMIC-to-MMIC interconnection is found to be between 0.54 to 1.88 dB. Another MMIC-to-MMIC interconnection method using a piece of CPW quartz board achieves 0.31 to 1.08 dB insertion loss.