Complementary pass gate logic implementation of 64-bit arithmetic logic unit using propagate, generate, and kill

An arithmetic logic unit (ALU) implemented with complementary pass gate logic using propagate, generate, and kill is provided. Broadly speaking, the ALU is a 64-bit ALU using a multi-stage global carry chain to generate intermediate fourth-bit carries that are folded with local four-bit sums to efficiently generate a final sum output. The ALU implements ones complement subtraction by incorporating a subtraction select signal to invert each bit of a second operand. The ALU circuitry implements a push-pull methodology to improve performance.