Ultra compact RFICs using three-dimensional MMIC technology

Since the 1980s, NTT has been developing three- dimensional (3D) monolith microwave integrated circuits (MMICs) to achieve small-size and low-cost ICs. The usage of 3D MMICs is a very powerful technique, especially at quasi-millimeter and millimeter wave. We describe the structure and features of 3D MMICs, introduce several MMIC subsystems, and point out future directions and plans for using 3D MMICs.