Hardware implementation of hyperbolic tangent and sigmoid activation functions

This paper presents the high accuracy hardware implementation of the hyperbolic tangent and sigmoid activation functions for artificial neural networks. A kind of a direct implementation of the functions in a few different versions is proposed and investigated both by software and hardware modeling. A single precision floating point arithmetic is applied. Apart from conventional design style with hardware description language coding, high level synthesis design techniques with the Matlab HDL coder and Xilinx Vivado HLS have also been investigated.