A novel 20 to 40 GHz monolithic passive differential coupler for MMICs applications

This paper presents the design and performance characteristics of a novel broadband passive differential coupler that has been developed for MMIC's applications. The new coupler utilizes a multi-dielectric layer structure to achieve a broadband performance from 20 to 40 GHz in a simple coplanar configuration. A return loss better than 20 dB, with an isolation of 25 dB have been achieved over the band of interest. Also a phase and amplitude mismatch better than 2/spl deg/ and 1 dB has been realized over the frequency band from 20 to 40 GHz. This performance is especially important to the intended use with wideband double balanced mixers, and amplifiers.