Heterogeneous Integration of Biasing Circuits for mmWave Reconfigurable Intelligent Surfaces

We present the design of a biasing circuit and interposer architecture for scalable millimeter wave (mmWave) reconfigurable intelligent surfaces (RISs). Specifically, a multilayer biasing board is designed to provide the necessary excitation of a 1-bit RIS. Ball grid array (BGA) technology is leveraged to integrate heterogeneous technologies and materials to provide more real estate on the RIS metasurface and more design flexibility. Fabrication and assembly challenges associated with this novel technique have been identified and recommendations for future fabrication/assembly are provided.