Low Insertion Losses Broadside Coupler in a Multilayer Above IC Technology for K-band Applications

This paper presents the design, fabrication and characterization of a 3 dB broadside K-band coupler integrated with a specifically developed low losses multi-layer above-IC technology. The combination of silicon surface micromachining with an associated design methodology of coplanar coupler indeed translates into low measured insertion losses of 0.25 dB at 20 GHz.Moreover, taking advantage of the multilayer technology, the investigated broadside configuration exhibits excellent compromise between strong coupling and wideband performances. A 3.9 dB coupling is achieved at 20 GHz with measured matching and isolation better than 14 dB and a broadband greater than 110%. This demonstrates the high potentialities of the proposed multilayer technology and associated design methodology to perform strong coupling and loss losses components and circuits.