A high-speed 4-bit ALU has been designed for 1 V operation to demonstrate the usefulness of the backgate forward substrate bias (BGFSB) method in 1.2 mm N-well CMOS technology. The 4-bit ALU employs a ripple carry adder and is capable of performing eight operations -four arithmetic and four logical operations. The BGFSB voltage has been limited to j0.4j V. Delay time measurements are taken for all operations from the SPICE simulations with and without the back-gate forward substrate bias. A speed advantage of a factor of about 2 -2.5 is obtained with BGFSB over the conventional design.