A novel 15 to 45 GHz monolithic passive balun for MMICs applications

This paper presents the design and performance characteristics of a novel broadband monolithic passive balun that has been developed for MMIC´s applications. The new balun utilizes a multi-dielectric layer structure to achieve a broadband performance of up to 3:1 in a simple coplanar configuration. A return loss better than 15 dB, with a maximum insertion loss of 4.5 dB including the 3 dB power splitting loss from 15 to 45 GHz has been realized. The developed balun also achieves better than 0.35 dB and 1.5/spl deg/ of amplitude and phase imbalance over the same frequency band. This performance is specially important to the intended use with wideband double balanced mixers, and amplifiers.