High performance with low implementation cost sigmoid generators

In this paper, a piecewise second order approximation method to compute the sigmoid function is proposed and evaluated. The scheme provides high performance and it is inexpensive to implement in terms of hardware. It requires one multiplication and two additions for the sigmoid computation. It provides better precision with an average error of 5.3*10^-3 which is less than other existing second/third order approaches having the average errors of 6.4*10^-2 and 7.8*10^-2 respectively. Finally the proposed scheme can provide a 1.15-1.67 speedup over existing schemes.