Computer arithmetic implemented with QCA: A progress report

This paper presents a review of designs for performing arithmetic operations with Quantum-Dot Cellular Automata (QCA). An overview of implementations of adders, multipliers and dividers is provided. Ripple carry, carry lookahead and conditional sum adder designs are compared. The rather surprising result is that with a carefully tailored full adder, ripple carry adders are faster in QCA than carry lookahead and conditional sum adders. Array and “fast” (Wallace and Dadda) multipliers are compared. Finally a Goldschmidt divider is implemented. All of the designs have been simulated with QCA Designer, a simulator that simplifies the estimation of area and delay.