High-Efficiency FPGA-Based Approximate Multipliers with LUT Sharing and Carry Switching

Approximate multiplier saves energy and improves hardware performance for error-tolerant computation-intensive applications. This work proposes hardware-efficient FPGA-based approximate multipliers with look-up table (LUT) sharing and carry switching. Sharing two LUTs with the same inputs enables to fully utilize the available LUT resources. To mitigate the accuracy loss incurred from this approach, the truncated carry is partially reserved by switching it to the adjacent calculation. In addition, we create a library of 8x8 approximate multipliers to provide various multiplication choices. The proposed design can provide enhancements of up to 38.75% in power, 17.29% in latency, and 28.17% in area compared to the Xilinx exact multiplier. Our proposed designs are open-source at https://github.com/YnuGuoLab/DATE_FPGA_Approx_Mul and assist in further reproducing and development.