Decimal Adders/Subtractors in FPGA: Efficient 6-input LUT Implementations

This paper presents FPGA implementations of add/subtract algorithms for 10´s complement BCD numbers. Carry-chain type circuits have been designed on 6-input LUT´s Xilinx Virtex-5 FPGA technologies. Some new concepts are reviewed to compute the P and G functions for carry-chain optimization purposes. Designs are presented with the corresponding time performances and area consumption figures. Results have been compared with 2´s complement binary implementations carried out on the same platform. Better time delays have been registered for decimal number within same range of operands.