Multilayer MMIC branch-line hybrid using thin dielectric layers

A miniature monolithic microwave integrated circuit (MMIC) branch-line hybrid circuit utilizing a multilayer structure composed of thin-film transmission lines is proposed. The branch-line hybrid circuit is designed for a center frequency of 20 GHz and fabricated in a 0.49-mm*0.53-mm area. A coupling loss of 5.5 dB+or-0.5 dB over a 3-GHz bandwidth is achieved.>