On current multi-drop backplanes, signal integrity is degraded due to impedance mismatches in the stubs and data rate on multi-drop bus is significantly degraded. In high-speed digital systems, a practical gigabit multi-drop I/O interface is based on asymmetrical broadband and lossless power splitter with the impedance matching. In this thesis, the analysis and design of 2D and 3D multi-drop I/O interface is discussed. Found the point-to-point 3D-I/O interface using inverter and SSTL logic signaling support up to 3 ~ 4 Gb/s regardless of impedance matching network, resulting in small impact of impedance matching network to P2P link. Found two key results 1) inverter 3D I/O using P2P with impedance match can work well up to 4Gb/s can be good design solution for high-speed 3D-IO 2) inverter using multi-drop and no impedance matching can’t work for future 3D multi-stacked I/O interface. The proposed 3D multi-stacked SSTL I/O using impedance matching can support up to 4Gb/s and in case of 8 stacked case, novel signaling 3D-I/O interface should be utilized.