VLSI implementation of pulse activated synapses

A generic circuit, the pulse stimulated charge pumping (PSCP) synapse, is presented. The PSCP synapse is a device based on charge pumping of interface states: it produces at its output a charge packet proportional to the number of pulses applied to its input, and to the electrically programmed density of interface states. It is particularly suitable for realising artificial neural networks in which the neuron activity is implemented as a pulse train, closely resembing the behaviour of biological neural networks. The PSCP synapse can be realised easily in less than 50µm², and has a large dynamic range. Preliminary experimental results are presented showing the current against frequency behaviour of the device, for various densities of interface states.