A 1024-bit, 1/2-rate fully parallel low-density parity-check (LDPC) code decoder has been designed and implemented using a three-dimensional (3D) 0.18μm fully depleted silicon-on-insulator (FDSOI) CMOS technology based on wafer bonding. The taped-out 3D decoder with about 8M transistors was simulated to have a high throughput of 2Gb/s and a low power consumption of only 430mW using 6.4μm by 6.3μm of die area. The 3D implementation is estimated to offer more than 10x power-delay-area product improvement over its corresponding 2D implementation. This first large-scale 3D ASIC with fine-grain (5μm) vertical interconnects is made possible by jointly developing a complete automated 3D design flow from a commercial 2-D design flow combined with the needed 3D-design point tools.