Hardware implementation of complex reaction-diffusion neural networks using log-domain techniques

This paper describes a hardware implementation of a 2nd order reaction-diffusion system. This hardware is able to emulate complex spatio-temporal behaviours that appear in nature, such as, travelling waves, spiral waves and Turing patterns. The hardware has been designed using log-domain techniques with MOS transistors operating in the subthreshold regime. In our implementation, the parameters of the reaction-diffusion equation are currents that can be adjusted several decades in order to reproduce different spatio-temporal behaviours. As a demonstrator, a linear array of 10 cells has been integrated in the AMS 0.35μm CMOS technology. We have experimentally reproduced three complex spatio-temporal phenomena: trigger and travelling wave propagation and the emulation of an oscillatory medium.