Soc design based on a FPGA for a configurable neural network trained by means of an EKF

Abstract

This work presents a configurable architecture for an artificial neural network implemented with a Field Programmable Gate Array (FPGA) in a System on Chip (SoC) environment. This architecture can reproduce the transfer function of different Multilayer Feedforward Neural Network (MFNN) configurations. The functionality of this configurable architecture relies on a single perceptron, multiplexers, and memory blocks that allow routing, storing, and processing information. The extended Kalman filter is the training algorithm that obtains the optimal weight values for the MFNN. The presented architecture was developed using Verilog Hardware Description Language, which permits designing hardware with a fair number of logical resources, and facilitates the portability to different FPGAs models without compatibility problems. A SoC that mainly incorporates a microprocessor and a FPGA is proposed, where the microprocessor is used for configuring the the MFNN and to enable and disable some functional blocks in the FPGA. The hardware was tested with measurements from a GaN class F power amplifier, using a 2.1 GHz Long Term Evolution signal with 5 MHz of bandwidth. In particular, a special case of an MFNN with two layers, i.e., a real-valued nonlinear autoregressive with an exogenous input neural network, was considered. The results reveal that a normalized mean square error value of −32.82 dB in steady-state was achievable, with a 71.36% generalization using unknown samples.