Accurate and Efficient Hyperbolic Tangent Activation Function on FPGA using the DCT Interpolation Filter (Abstract Only)

Implementing an accurate and fast activation function with low cost is a crucial aspect to the implementation of Deep Neural Networks (DNNs) on FPGAs. We propose a high accuracy approximation approach for the hyperbolic tangent activation function of artificial neurons in DNNs. It is based on the Discrete Cosine Transform Interpolation Filter (DCTIF). The proposed interpolation architecture combines simple arithmetic operations on the stored samples of the hyperbolic tangent function and on input data. The proposed implementation outperforms the existing implementations in terms of accuracy while using the same or fewer computational and memory resources. The proposed architecture can approximate the hyperbolic tangent activation function with 2×10-4 maximum error while requiring only 1.12 Kbits memory and 21 LUTs of a Virtex-7 FPGA.