Digital-Coding Metamaterials for On-Chip Beamsteering and Reconfigurable Millimeter-Wave Interconnects

On-chip millimeter-wave interconnects are becoming crucial for advancing on-chip and inter-chip transmission technologies, improving transmission efficiency and system scalability, especially in Wireless Network-on-Chip (WiNoC) and chip-scale 2.5D and 3D integration. However, due to the inherent limitations of on-chip integration related to antenna size and microfabrication compatibility. On-chip wireless channels often necessitate the use of compact, planar antennas. These antennas typically suffer from limited transmission gain, lack of beam control, and poor interference immunity, posing challenges to the reliability and versatility of millimeter-wave interconnects. This paper presents a 1-bit digital-coding metamaterial to address these challenges. The metamaterial features a 3x5 tunable unit-cell array, with each cell switchable between the '0' or '1' state with a distinct refractive index. The refractive index distribution within the unit cell array can be controlled through different binary coding sequences to manipulate the electromagnetic waves and achieve different transmission functions. When integrated with an on-chip dipole antenna, the metamaterial can achieve adjustable beamsteering in the range of +/- 40(degrees) , 3.3 dB transmission gain enhancement, 90 degrees beam splitting, and efficient energy attenuation. The proposed digital-coding metamaterial allows precise control and reconfiguration of the wireless signal distribution on silicon, significantly enhancing the flexibility, efficiency, and scalability of on-chip millimeter-wave communications.