409ps 4.7 FO4 64b adder based on output prediction logic in 0.18um CMOS

We present a fast 64b adder based on output prediction logic (OPL) that has a measured worst-case delay of 409ps, equivalent to 4.7 FO4 inverter delays for the TSMC 0.18/spl mu/m process that was used for fabrication. This normalized delay is 1.45X faster than the fastest previously reported 64b adder. The adder uses a modified radix-3 Kogge-Stone architecture and has 5 logic levels.