A compact wideband ring mixer utilizing a pair of PLANAR transitions for phase inversion

A new design of a compact wideband ring mixer is introduced in this article. The proposed mixer utilizes a compact ring structure comprising a pair of ultra-wideband planar in-phase and inverted-phase transitions as a mixer balun. The implemented mixer has a number of desirable features such as wide bandwidth (∼120%), compact size, excellent port-to-port isolations, and return loss. The size of the proposed mixer is 33.2% of the conventional single-balanced ring mixers. The measured results show flat conversion loss of ∼8.5 dB and greater than 20 dB port-to-port isolation from 3 to 12 GHz.