A novel three-dimensional FPGA architecture with high-speed serial communication links

Three-dimensional (3D) integrated circuit technology is expected to offer continual improvement to very-large-scale integration performance as the process of miniaturization approaches physical limits. However, because the through-silicon vias (TSVs) that are used to create interlayer vertical connections are much larger area than transistors, there is an inherent tradeoff between connectivity and small size. Field-programmable gate arrays (FPGAs) are particularly noted for requiring a high level of routing resources, which means that it is unrealistic to make the same number of connections vertically as horizontally. In previous research, we proposed a method for creating a two-layer compact 3D FPGA with face-down integration (the base FPGA). In this paper, we discuss stacking multiple base FPGAs by the face-up method and propose a method for achieving highspeed interlayer communications with TSV serial connections. The proposed architecture improves FPGA performance by using smaller TSVs. The evaluation results show that the proposed 3D FPGA can achieve a total area that is as low as 67% the equivalent two-dimensional FPGA.