An Ultra-Wideband Balun Using Multi-Metal GaAs MMIC Technology

In this paper, we demonstrate an ultra-wideband MMIC Marchand balun that utilizes a two-layer benzocyclobutene (BCB) GaAs MMIC process with a total of 4 metal layers. This multi-metal technology is built upon a standard GaAs HEMT technology with full compatibility. The fabricated balun achieved an approximately 11:1 bandwidth from 2 to 22 GHz, with less than 3-degree maximum phase imbalance, and less than 1 dB maximum amplitude imbalance. To our knowledge, this is the largest bandwidth ratio ever reported for an MMIC Marchand balun.