An improved reciprocal approximation algorithm for a Newton Raphson divider

Abstract

Newton Raphson Functional Approximation is an attractive division strategy that provides quadratic convergence. With appropriate computational resources, it can be faster than digit recurrence methods if an accurate initial approximation is available. Several table lookup based initial approximation methods have been proposed previously. This paper examines some of these methods and implements a 24 bit divider utilizing a ROM smaller than 1 Kb. A Taylor series based reciprocal approximation method is used that employs a table lookup followed by multiplication. Simulations confirm that the design achieves desired accuracy after one Newton Raphson iteration.